ash / wm / overview / overview_session.cc [blame]

// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ash/wm/overview/overview_session.h"

#include <utility>

#include "ash/accessibility/accessibility_controller.h"
#include "ash/app_list/app_list_controller_impl.h"
#include "ash/constants/ash_features.h"
#include "ash/frame_throttler/frame_throttling_controller.h"
#include "ash/metrics/user_metrics_recorder.h"
#include "ash/public/cpp/window_properties.h"
#include "ash/root_window_controller.h"
#include "ash/root_window_settings.h"
#include "ash/screen_util.h"
#include "ash/shell.h"
#include "ash/style/rounded_label_widget.h"
#include "ash/wm/desks/desk.h"
#include "ash/wm/desks/desk_textfield.h"
#include "ash/wm/desks/desks_util.h"
#include "ash/wm/desks/overview_desk_bar_view.h"
#include "ash/wm/desks/templates/saved_desk_dialog_controller.h"
#include "ash/wm/desks/templates/saved_desk_grid_view.h"
#include "ash/wm/desks/templates/saved_desk_item_view.h"
#include "ash/wm/desks/templates/saved_desk_library_view.h"
#include "ash/wm/desks/templates/saved_desk_presenter.h"
#include "ash/wm/desks/templates/saved_desk_util.h"
#include "ash/wm/mru_window_tracker.h"
#include "ash/wm/overview/birch/birch_bar_controller.h"
#include "ash/wm/overview/birch/birch_bar_util.h"
#include "ash/wm/overview/birch/tab_app_selection_host.h"
#include "ash/wm/overview/overview_controller.h"
#include "ash/wm/overview/overview_delegate.h"
#include "ash/wm/overview/overview_grid.h"
#include "ash/wm/overview/overview_item.h"
#include "ash/wm/overview/overview_item_view.h"
#include "ash/wm/overview/overview_utils.h"
#include "ash/wm/overview/overview_window_drag_controller.h"
#include "ash/wm/overview/scoped_float_container_stacker.h"
#include "ash/wm/overview/scoped_overview_animation_settings.h"
#include "ash/wm/snap_group/snap_group.h"
#include "ash/wm/snap_group/snap_group_controller.h"
#include "ash/wm/snap_group/snap_group_metrics.h"
#include "ash/wm/splitview/split_view_controller.h"
#include "ash/wm/splitview/split_view_overview_session.h"
#include "ash/wm/splitview/split_view_utils.h"
#include "ash/wm/window_properties.h"
#include "ash/wm/window_restore/informed_restore_controller.h"
#include "ash/wm/window_state.h"
#include "ash/wm/window_util.h"
#include "base/auto_reset.h"
#include "base/containers/contains.h"
#include "base/functional/bind.h"
#include "base/memory/raw_ptr.h"
#include "base/metrics/histogram_macros.h"
#include "base/metrics/user_metrics.h"
#include "base/ranges/algorithm.h"
#include "base/task/single_thread_task_runner.h"
#include "base/trace_event/trace_event.h"
#include "chromeos/utils/haptics_util.h"
#include "ui/aura/client/aura_constants.h"
#include "ui/compositor/layer.h"
#include "ui/display/screen.h"
#include "ui/display/tablet_state.h"
#include "ui/events/devices/haptic_touchpad_effects.h"
#include "ui/events/event.h"
#include "ui/views/accessibility/view_accessibility.h"
#include "ui/views/view_utils.h"
#include "ui/views/widget/widget.h"
#include "ui/wm/core/coordinate_conversion.h"
#include "ui/wm/core/scoped_animation_disabler.h"
#include "ui/wm/core/window_util.h"

namespace ash {

namespace {

// Values for scrolling the grid by using the keyboard.
constexpr int kKeyboardPressScrollingDp = 75;
constexpr int kKeyboardHoldScrollingDp = 15;

// Tries to end overview. Returns true if overview is successfully ended, or
// just was not active in the first place.
bool EndOverview(OverviewEndAction action) {
  return OverviewController::Get()->EndOverview(action);
}

// Returns the window to be activated when the given `overview_item` is
// selected.
aura::Window* GetWindowForSelection(
    OverviewItemBase* overview_item,
    const std::vector<raw_ptr<aura::Window, VectorExperimental>>& window_list) {
  const auto item_windows = overview_item->GetWindows();
  CHECK(!item_windows.empty());
  if (item_windows.size() == 1u) {
    return item_windows[0];
  }

  // When the given `overview_item` is a group item, return the first window in
  // the `window_list` that is contained in `item_windows`.
  for (aura::Window* window : window_list) {
    if (base::Contains(item_windows, window)) {
      return window;
    }
  }

  NOTREACHED();
}

// A self-deleting window state observer that runs the given callback when its
// associated window state has been changed.
class AsyncWindowStateChangeObserver : public WindowStateObserver,
                                       public aura::WindowObserver {
 public:
  AsyncWindowStateChangeObserver(
      aura::Window* window,
      base::OnceCallback<void(WindowState*)> on_post_window_state_changed)
      : window_(window),
        on_post_window_state_changed_(std::move(on_post_window_state_changed)) {
    DCHECK(!on_post_window_state_changed_.is_null());
    WindowState::Get(window_)->AddObserver(this);
    window_->AddObserver(this);
  }

  ~AsyncWindowStateChangeObserver() override { RemoveAllObservers(); }

  AsyncWindowStateChangeObserver(const AsyncWindowStateChangeObserver&) =
      delete;
  AsyncWindowStateChangeObserver& operator=(
      const AsyncWindowStateChangeObserver&) = delete;

  // aura::WindowObserver:
  void OnWindowDestroying(aura::Window* window) override { delete this; }

  // WindowStateObserver:
  void OnPostWindowStateTypeChange(WindowState* window_state,
                                   chromeos::WindowStateType) override {
    RemoveAllObservers();
    std::move(on_post_window_state_changed_).Run(window_state);
    delete this;
  }

 private:
  void RemoveAllObservers() {
    WindowState::Get(window_)->RemoveObserver(this);
    window_->RemoveObserver(this);
  }

  raw_ptr<aura::Window> window_;

  base::OnceCallback<void(WindowState*)> on_post_window_state_changed_;
};

}  // namespace

OverviewSession::OverviewSession(OverviewDelegate* delegate)
    : delegate_(delegate),
      chromevox_enabled_(Shell::Get()
                             ->accessibility_controller()
                             ->spoken_feedback()
                             .enabled()) {
  DCHECK(delegate_);
  Shell::Get()->AddPreTargetHandler(this);
}

OverviewSession::~OverviewSession() {
  // Don't delete |window_drag_controller_| yet since the stack might be still
  // using it.
  if (window_drag_controller_) {
    window_drag_controller_->ResetOverviewSession();
    base::SingleThreadTaskRunner::GetCurrentDefault()->DeleteSoon(
        FROM_HERE, window_drag_controller_.release());
  }
}

// NOTE: The work done in Init() is not done in the constructor because it may
// cause other, unrelated classes, to make indirect method calls on a partially
// constructed object.
void OverviewSession::Init(
    const aura::Window::Windows& windows,
    const aura::Window::Windows& hide_windows,
    base::WeakPtr<WindowOcclusionCalculator> window_occlusion_calculator) {
  TRACE_EVENT0("ui", "OverviewSession::Init");

  Shell::Get()->AddShellObserver(this);

  if (saved_desk_util::ShouldShowSavedDesksOptions()) {
    hide_windows_for_saved_desks_grid_ = std::make_unique<
        ScopedOverviewHideWindows>(
        /*windows=*/std::vector<raw_ptr<aura::Window, VectorExperimental>>{},
        /*forced_hidden=*/true);
  }

  hide_overview_windows_ = std::make_unique<ScopedOverviewHideWindows>(
      std::move(hide_windows), /*force_hidden=*/false);

  active_window_before_overview_ = window_util::GetActiveWindow();
  if (active_window_before_overview_) {
    active_window_before_overview_observation_.Observe(
        active_window_before_overview_.get());
  }

  // Create this before the desks bar widget.
  if (saved_desk_util::ShouldShowSavedDesksOptions() &&
      !saved_desk_presenter_) {
    saved_desk_presenter_ = std::make_unique<SavedDeskPresenter>(this);
    saved_desk_dialog_controller_ =
        std::make_unique<SavedDeskDialogController>();
  }

  // Create this before the birch bar widget.
  if (features::IsForestFeatureEnabled()) {
    birch_bar_controller_ = std::make_unique<BirchBarController>(
        /*is_informed_restore=*/enter_exit_overview_type_ ==
        OverviewEnterExitType::kInformedRestore);
    if (enter_exit_overview_type_ == OverviewEnterExitType::kInformedRestore) {
      PostLoginMetricsRecorder* post_login_metrics_recorder =
          Shell::Get()
              ->login_unlock_throughput_recorder()
              ->post_login_metrics_recorder();
      if (birch_bar_controller_->GetShowBirchSuggestions()) {
        post_login_metrics_recorder->set_post_login_ui_status(
            PostLoginMetricsRecorder::PostLoginUIStatus::kShownWithBirchBar);
      } else {
        post_login_metrics_recorder->set_post_login_ui_status(
            PostLoginMetricsRecorder::PostLoginUIStatus::kShownWithoutBirchBar);
      }
    }
  }

  aura::Window::Windows root_windows = Shell::GetAllRootWindows();
  std::sort(root_windows.begin(), root_windows.end(),
            [](const aura::Window* a, const aura::Window* b) {
              // Since we don't know if windows are vertically or horizontally
              // oriented we use both x and y position. This may be confusing
              // if you have 3 or more monitors which are not strictly
              // horizontal or vertical but that case is not yet supported.
              return (a->GetBoundsInScreen().x() + a->GetBoundsInScreen().y()) <
                     (b->GetBoundsInScreen().x() + b->GetBoundsInScreen().y());
            });

  for (aura::Window* root : root_windows) {
    auto grid = std::make_unique<OverviewGrid>(root, windows, this,
                                               window_occlusion_calculator);
    grid_list_.push_back(std::move(grid));
  }

  // The calls to OverviewGrid::PrepareForOverview() requires some
  // LayoutManagers to perform layouts so that windows are correctly visible and
  // properly animated in overview mode. Otherwise these layouts should be
  // suppressed during overview mode so they don't conflict with overview mode
  // animations.

  // Do not call PrepareForOverview until all items are added to `item_list_`
  // as we don't want to cause any window updates until all windows in
  // overview are observed. See http://crbug.com/384495.
  for (std::unique_ptr<OverviewGrid>& overview_grid : grid_list_) {
    overview_grid->PrepareForOverview();

    // If we are entering because of a continuous scroll, don't
    // position overview items for starting a continuous scroll as we will
    // place them during future scroll updates.
    if (enter_exit_overview_type_ ==
        OverviewEnterExitType::kContinuousAnimationEnterOnScrollUpdate) {
      break;
    }

    if (ShouldEnterWithoutAnimations()) {
      overview_grid->PositionWindows(/*animate=*/false);
      continue;
    }

    // Exit only types should not appear here.
    DCHECK_NE(enter_exit_overview_type_, OverviewEnterExitType::kFadeOutExit);
    overview_grid->PositionWindows(/*animate=*/true, /*ignored_items=*/{},
                                   OverviewTransition::kEnter);
  }

  // TODO(http://b/326091611): In the case of dragging a window from the shelf
  // with one window total, this will create the no windows widget. Then, we
  // will be notified the drag has started and a drop target will be added,
  // hiding the no windows widget. This all happens before the frame is
  // presented so it looks ok from the users perspective, but we should avoid
  // creating it in the first place.
  const bool is_continuous_enter =
      enter_exit_overview_type_ ==
      OverviewEnterExitType::kContinuousAnimationEnterOnScrollUpdate;
  const bool animate = !is_continuous_enter && !ShouldEnterWithoutAnimations();
  UpdateNoWindowsWidgetOnEachGrid(animate, is_continuous_enter);

  // Create the widget that will receive focus while in overview mode for
  // accessibility purposes. Make its role a button as the contents so that
  // `UpdateAccessibilityFocus` can put it on the accessibility focus
  // cycler.
  views::Widget::InitParams params(
      views::Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET,
      views::Widget::InitParams::TYPE_WINDOW_FRAMELESS);
  params.opacity = views::Widget::InitParams::WindowOpacity::kTranslucent;
  params.accept_events = false;
  params.bounds = gfx::Rect(0, 0, 2, 2);
  params.layer_type = ui::LAYER_NOT_DRAWN;
  params.name = "OverviewModeFocusWidget";
  params.z_order = ui::ZOrderLevel::kFloatingWindow;
  params.init_properties_container.SetProperty(kExcludeInMruKey, true);
  overview_focus_widget_ = std::make_unique<views::Widget>(std::move(params));
  overview_focus_widget_->SetContentsView(
      views::Builder<views::View>()
          .SetAccessibleName(std::u16string(),
                             ax::mojom::NameFrom::kAttributeExplicitlyEmpty)
          .SetAccessibleRole(ax::mojom::Role::kButton)
          .SetFocusBehavior(views::View::FocusBehavior::ACCESSIBLE_ONLY)
          .Build());

  num_start_windows_ = GetNumWindows();
  UMA_HISTOGRAM_COUNTS_100("Ash.Overview.Items", num_start_windows_);

  SplitViewController::Get(Shell::GetPrimaryRootWindow())->AddObserver(this);

  if (SnapGroupController* snap_group_controller = SnapGroupController::Get()) {
    snap_group_controller->AddObserver(this);
  }

  display_observer_.emplace(this);
  base::RecordAction(base::UserMetricsAction("WindowSelector_Overview"));
  // Send an a11y alert.
  Shell::Get()->accessibility_controller()->TriggerAccessibilityAlert(
      AccessibilityAlert::WINDOW_OVERVIEW_MODE_ENTERED);

  desks_controller_observation_.Observe(DesksController::Get());

  ignore_activations_ = false;
}

// NOTE: The work done in `Shutdown()` is not done in the destructor because it
// may cause other, unrelated classes, to make indirect calls to
// `restoring_minimized_windows()` on a partially destructed object.
void OverviewSession::Shutdown() {
  TRACE_EVENT0("ui", "OverviewSession::Shutdown");

  bool was_saved_desk_library_showing = false;
  for (auto& grid : grid_list_) {
    if (grid->IsShowingSavedDeskLibrary()) {
      was_saved_desk_library_showing = true;
      break;
    }
  }

  // This should have been set already when the process of ending overview mode
  // began. See OverviewController::OnSelectionEnded().
  DCHECK(is_shutting_down_);

  if (SnapGroupController* snap_group_controller = SnapGroupController::Get()) {
    snap_group_controller->RemoveObserver(this);
  }

  desks_controller_observation_.Reset();
  if (observing_desk_) {
    for (aura::Window* root : Shell::GetAllRootWindows()) {
      observing_desk_->GetDeskContainerForRoot(root)->RemoveObserver(this);
    }
  }

  Shell::Get()->RemovePreTargetHandler(this);
  Shell::Get()->RemoveShellObserver(this);

  float_container_stacker_.reset();

  // Stop the presenter from receiving any events that may update the model or
  // UI.
  saved_desk_presenter_.reset();

  // Resetting here will close any dialogs, and DCHECK anyone trying to open a
  // dialog past this point.
  saved_desk_dialog_controller_.reset();

  // Resetting the birch bar controller before shutting down overview grids to
  // avoid dangling pointers.
  birch_bar_controller_.reset();

  // Stop observing screen metrics changes first to avoid auto-positioning
  // windows in response to work area changes from window activation.
  display_observer_.reset();

  weak_ptr_factory_.InvalidateWeakPtrs();

  // Stop observing split view state changes before restoring window focus.
  // Otherwise the activation of the window triggers OnSplitViewStateChanged()
  // that will call into this function again.
  SplitViewController::Get(Shell::GetPrimaryRootWindow())->RemoveObserver(this);

  size_t remaining_items = 0;
  for (std::unique_ptr<OverviewGrid>& overview_grid : grid_list_) {
    // During shutdown, do not animate all windows in overview if we need to
    // animate the snapped window.
    if (overview_grid->should_animate_when_exiting() &&
        enter_exit_overview_type_ != OverviewEnterExitType::kImmediateExit) {
      overview_grid->CalculateWindowListAnimationStates(
          selected_item_ &&
                  selected_item_->overview_grid() == overview_grid.get()
              ? selected_item_.get()
              : nullptr,
          OverviewTransition::kExit, /*target_bounds=*/{});
    }
    for (const auto& overview_item : overview_grid->item_list()) {
      overview_item->RestoreWindow(/*reset_transform=*/true,
                                   /*animate=*/!was_saved_desk_library_showing);
    }
  }

  // Setting focus after restoring windows' state avoids unnecessary animations.
  // No need to restore if we are fading out to the home launcher screen, as all
  // windows will be minimized.
  const bool should_restore =
      enter_exit_overview_type_ == OverviewEnterExitType::kNormal ||
      enter_exit_overview_type_ == OverviewEnterExitType::kImmediateExit;
  RestoreWindowActivation(should_restore);
  RemoveAllObservers();

  for (std::unique_ptr<OverviewGrid>& overview_grid : grid_list_)
    overview_grid->Shutdown(enter_exit_overview_type_);

  if (!was_saved_desk_library_showing) {
    UMA_HISTOGRAM_COUNTS_100("Ash.Overview.OverviewClosedItems",
                             num_start_windows_ - remaining_items);
  }

  // Explicitly clear the `selected_item_` to avoid dangling raw_ptr detection.
  selected_item_ = nullptr;
  grid_list_.clear();

  // Hide the focus widget on overview session end to prevent it from retaining
  // focus and handling key press events now that overview session is not
  // consuming them.
  if (overview_focus_widget_) {
    overview_focus_widget_->Hide();
  }
}

void OverviewSession::OnGridEmpty() {
  if (!IsEmpty())
    return;

  if (SplitViewController::Get(Shell::GetPrimaryRootWindow())
          ->InTabletSplitViewMode()) {
    UpdateNoWindowsWidgetOnEachGrid(/*animate=*/true,
                                    /*is_continuous_enter=*/false);
  } else if (!allow_empty_desk_without_exiting_ &&
             !IsShowingSavedDeskLibrary()) {
    EndOverview(OverviewEndAction::kLastWindowRemoved);
  }
}

void OverviewSession::IncrementSelection(bool forward) {
  Move(/*reverse=*/!forward);
}

bool OverviewSession::AcceptSelection() {
  return focus_cycler_.AcceptSelection();
}

void OverviewSession::SelectWindow(OverviewItemBase* item) {
  // `BuildWindowListIgnoreModal()` is used here to make sure the main window is
  // included in the `window_list` with the existence of modal transient
  // window(s) which makes the main window not activatable.
  const aura::Window::Windows window_list =
      Shell::Get()->mru_window_tracker()->BuildWindowListIgnoreModal(
          kActiveDesk);

  const auto windows = item->GetWindows();
  CHECK(!windows.empty());
  aura::Window* window = windows.size() > 1u
                             ? GetWindowForSelection(item, window_list)
                             : windows[0].get();

  if (!window_list.empty()) {
    // Record `WindowSelector_ActiveWindowChanged` if the user is selecting a
    // window other than the window that was active prior to entering overview
    // mode (i.e., the window at the front of the MRU list).
    if (window_list[0] != window) {
      base::RecordAction(
          base::UserMetricsAction("WindowSelector_ActiveWindowChanged"));
      Shell::Get()->metrics()->task_switch_metrics_recorder().OnTaskSwitch(
          TaskSwitchSource::OVERVIEW_MODE);
    }

    if (const auto it = base::ranges::find(window_list, window);
        it != window_list.end()) {
      // Record 1-based index so that selecting a top MRU window will record 1.
      UMA_HISTOGRAM_COUNTS_100("Ash.Overview.SelectionDepth",
                               1 + it - window_list.begin());
    }
  }

  item->EnsureVisible();

  if (window->GetProperty(kPipOriginalWindowKey)) {
    window_util::ExpandArcPipWindow();
    return;
  }

  // If the selected window is a minimized window, un-minimize it first before
  // activating it so that the window can use the scale-up animation instead of
  // un-minimizing animation. The activation of the window will happen in an
  // asynchronous manner on window state has been changed. That's because some
  // windows (ARC app windows) have their window states changed async, so we
  // need to wait until the window is fully unminimized before activation as
  // opposed to having two consecutive calls.
  auto* window_state = WindowState::Get(window);
  SplitViewController* split_view_controller = SplitViewController::Get(window);
  const bool in_split_view = split_view_controller->InSplitViewMode();
  if (window_state->IsMinimized()) {
    wm::ScopedAnimationDisabler disabler(window);
    // The following instance self-destructs when the window state changed.
    new AsyncWindowStateChangeObserver(
        window, base::BindOnce([](WindowState* window_state) {
          for (auto* window_iter : window_util::GetVisibleTransientTreeIterator(
                   window_state->window())) {
            window_iter->layer()->SetOpacity(1.0);
          }
          wm::ActivateWindow(window_state->window());
        }));

    // If we are in split mode, use Show() here to delegate un-minimizing to
    // SplitViewController as it handles auto snapping cases.
    if (in_split_view) {
      window->Show();
    } else {
      window_state->Unminimize();
    }
    return;
  }

  // If any window within a snap group is selected for snapping in partial
  // Overview, break the Snap Group it belongs to in order to form a new Snap
  // Group between the already snapped window and the newly selected window.
  if (in_split_view) {
    if (SnapGroupController* snap_group_controller =
            SnapGroupController::Get()) {
      if (SnapGroup* snap_group =
              snap_group_controller->GetSnapGroupForGivenWindow(window);
          snap_group &&
          window != split_view_controller->GetDefaultSnappedWindow()) {
        snap_group_controller->RemoveSnapGroup(
            snap_group,
            SnapGroupExitPoint::kSelectWindowInSnapGroupInPartialOverview);
      }
    }
  }

  wm::ActivateWindow(window);
}

void OverviewSession::SetSplitViewDragIndicatorsDraggedWindow(
    aura::Window* dragged_window) {
  for (std::unique_ptr<OverviewGrid>& grid : grid_list_)
    grid->SetSplitViewDragIndicatorsDraggedWindow(dragged_window);
}

void OverviewSession::UpdateSplitViewDragIndicatorsWindowDraggingStates(
    const aura::Window* root_window_being_dragged_in,
    SplitViewDragIndicators::WindowDraggingState
        state_on_root_window_being_dragged_in) {
  if (state_on_root_window_being_dragged_in ==
      SplitViewDragIndicators::WindowDraggingState::kNoDrag) {
    ResetSplitViewDragIndicatorsWindowDraggingStates();
    return;
  }
  for (std::unique_ptr<OverviewGrid>& grid : grid_list_) {
    grid->SetSplitViewDragIndicatorsWindowDraggingState(
        grid->root_window() == root_window_being_dragged_in
            ? state_on_root_window_being_dragged_in
            : SplitViewDragIndicators::WindowDraggingState::kOtherDisplay);
  }
}

void OverviewSession::ResetSplitViewDragIndicatorsWindowDraggingStates() {
  for (std::unique_ptr<OverviewGrid>& grid : grid_list_) {
    grid->SetSplitViewDragIndicatorsWindowDraggingState(
        SplitViewDragIndicators::WindowDraggingState::kNoDrag);
  }
}

void OverviewSession::RearrangeDuringDrag(OverviewItemBase* dragged_item) {
  for (std::unique_ptr<OverviewGrid>& grid : grid_list_) {
    DCHECK(grid->split_view_drag_indicators());
    grid->RearrangeDuringDrag(
        dragged_item,
        grid->split_view_drag_indicators()->current_window_dragging_state());
  }
}

void OverviewSession::UpdateDropTargetsBackgroundVisibilities(
    OverviewItemBase* dragged_item,
    const gfx::PointF& location_in_screen) {
  for (std::unique_ptr<OverviewGrid>& grid : grid_list_) {
    if (grid->drop_target()) {
      grid->UpdateDropTargetBackgroundVisibility(dragged_item,
                                                 location_in_screen);
    }
  }
}

OverviewGrid* OverviewSession::GetGridWithRootWindow(
    aura::Window* root_window) {
  for (std::unique_ptr<OverviewGrid>& grid : grid_list_) {
    if (grid->root_window() == root_window)
      return grid.get();
  }

  return nullptr;
}

void OverviewSession::AddItem(
    aura::Window* window,
    bool reposition,
    bool animate,
    const base::flat_set<OverviewItemBase*>& ignored_items,
    size_t index) {
  // Early exit if a grid already contains |window|.
  OverviewGrid* grid = GetGridWithRootWindow(window->GetRootWindow());
  if (!grid || grid->GetOverviewItemContaining(window))
    return;

  base::AutoReset<bool> ignore(&ignore_activations_, true);
  grid->AddItem(window, reposition, animate, ignored_items, index,
                /*use_spawn_animation=*/false, /*restack=*/false);
  OnItemAdded(window);
}

void OverviewSession::AppendItem(aura::Window* window,
                                 bool reposition,
                                 bool animate) {
  // Early exit if a grid already contains |window|.
  OverviewGrid* grid = GetGridWithRootWindow(window->GetRootWindow());
  if (!grid || grid->GetOverviewItemContaining(window))
    return;

  if (IsShowingSavedDeskLibrary())
    animate = false;

  base::AutoReset<bool> ignore(&ignore_activations_, true);
  grid->AppendItem(window, reposition, animate, /*use_spawn_animation=*/true);
  OnItemAdded(window);
}

void OverviewSession::AddItemInMruOrder(aura::Window* window,
                                        bool reposition,
                                        bool animate,
                                        bool restack,
                                        bool use_spawn_animation) {
  // Early exit if a grid already contains |window|.
  OverviewGrid* grid = GetGridWithRootWindow(window->GetRootWindow());
  if (!grid || grid->GetOverviewItemContaining(window))
    return;

  base::AutoReset<bool> ignore(&ignore_activations_, true);
  grid->AddItemInMruOrder(window, reposition, animate, restack,
                          use_spawn_animation);
  OnItemAdded(window);
}

void OverviewSession::RemoveItem(OverviewItemBase* overview_item) {
  RemoveItem(overview_item, /*item_destroying=*/false, /*reposition=*/false);
}

void OverviewSession::RemoveItem(OverviewItemBase* overview_item,
                                 bool item_destroying,
                                 bool reposition) {
  if (overview_item->GetWindow() == active_window_before_overview_) {
    active_window_before_overview_observation_.Reset();
    active_window_before_overview_ = nullptr;
  }

  overview_item->overview_grid()->RemoveItem(overview_item, item_destroying,
                                             reposition);

  UpdateNoWindowsWidgetOnEachGrid(/*animate=*/true,
                                  /*is_continuous_enter=*/false);
  UpdateAccessibilityFocus();
}

void OverviewSession::RemoveDropTargets() {
  for (std::unique_ptr<OverviewGrid>& grid : grid_list_) {
    if (grid->drop_target()) {
      grid->RemoveDropTarget();
    }
  }
}

void OverviewSession::InitiateDrag(OverviewItemBase* item,
                                   const gfx::PointF& location_in_screen,
                                   bool is_touch_dragging,
                                   OverviewItemBase* event_source_item) {
  if (OverviewController::Get()->IsInStartAnimation() ||
      SplitViewController::Get(Shell::GetPrimaryRootWindow())
          ->IsDividerAnimating()) {
    return;
  }

  window_drag_controller_ = std::make_unique<OverviewWindowDragController>(
      this, item, is_touch_dragging, event_source_item);
  window_drag_controller_->InitiateDrag(location_in_screen);

  for (std::unique_ptr<OverviewGrid>& grid : grid_list_) {
    grid->OnOverviewItemDragStarted();
    grid->UpdateSaveDeskButtons();
  }

  // Fire a haptic event if necessary.
  if (!is_touch_dragging) {
    chromeos::haptics_util::PlayHapticTouchpadEffect(
        ui::HapticTouchpadEffect::kTick,
        ui::HapticTouchpadEffectStrength::kMedium);
  }
}

void OverviewSession::Drag(OverviewItemBase* item,
                           const gfx::PointF& location_in_screen) {
  DCHECK(window_drag_controller_);
  DCHECK_EQ(item, window_drag_controller_->item());
  window_drag_controller_->Drag(location_in_screen);
}

void OverviewSession::CompleteDrag(OverviewItemBase* item,
                                   const gfx::PointF& location_in_screen) {
  DCHECK(window_drag_controller_);
  DCHECK_EQ(item, window_drag_controller_->item());

  const bool snap = window_drag_controller_->CompleteDrag(location_in_screen) ==
                    OverviewWindowDragController::DragResult::kSnap;
  for (std::unique_ptr<OverviewGrid>& grid : grid_list_) {
    grid->OnOverviewItemDragEnded(snap);
    grid->UpdateSaveDeskButtons();
  }
}

void OverviewSession::StartNormalDragMode(
    const gfx::PointF& location_in_screen) {
  window_drag_controller_->StartNormalDragMode(location_in_screen);
}

void OverviewSession::Fling(OverviewItemBase* item,
                            const gfx::PointF& location_in_screen,
                            float velocity_x,
                            float velocity_y) {
  // Its possible a fling event is not paired with a tap down event. Ignore
  // these flings.
  if (!window_drag_controller_ || item != window_drag_controller_->item())
    return;

  const bool snap = window_drag_controller_->Fling(location_in_screen,
                                                   velocity_x, velocity_y) ==
                    OverviewWindowDragController::DragResult::kSnap;
  for (std::unique_ptr<OverviewGrid>& grid : grid_list_) {
    grid->OnOverviewItemDragEnded(snap);
    grid->UpdateSaveDeskButtons();
  }
}

void OverviewSession::ActivateDraggedWindow() {
  window_drag_controller_->ActivateDraggedWindow();
}

void OverviewSession::ResetDraggedWindowGesture() {
  window_drag_controller_->ResetGesture();
  for (std::unique_ptr<OverviewGrid>& grid : grid_list_) {
    grid->OnOverviewItemDragEnded(/*snap=*/false);
    grid->UpdateSaveDeskButtons();
  }
}

void OverviewSession::OnWindowDragStarted(aura::Window* dragged_window,
                                          bool animate) {
  OverviewGrid* target_grid =
      GetGridWithRootWindow(dragged_window->GetRootWindow());
  if (!target_grid)
    return;
  target_grid->OnWindowDragStarted(dragged_window, animate);

  // The stacker object may be already created depending on the overview enter
  // type.
  if (!float_container_stacker_) {
    float_container_stacker_ = std::make_unique<ScopedFloatContainerStacker>();
  }
  float_container_stacker_->OnDragStarted(dragged_window);
}

void OverviewSession::OnWindowDragContinued(
    aura::Window* dragged_window,
    const gfx::PointF& location_in_screen,
    SplitViewDragIndicators::WindowDraggingState window_dragging_state) {
  OverviewGrid* target_grid =
      GetGridWithRootWindow(dragged_window->GetRootWindow());
  if (!target_grid)
    return;
  target_grid->OnWindowDragContinued(dragged_window, location_in_screen,
                                     window_dragging_state);
}

void OverviewSession::OnWindowDragEnded(aura::Window* dragged_window,
                                        const gfx::PointF& location_in_screen,
                                        bool should_drop_window_into_overview,
                                        bool snap) {
  DCHECK(float_container_stacker_);
  float_container_stacker_->OnDragFinished(dragged_window);

  OverviewGrid* target_grid =
      GetGridWithRootWindow(dragged_window->GetRootWindow());
  if (!target_grid)
    return;
  target_grid->OnWindowDragEnded(dragged_window, location_in_screen,
                                 should_drop_window_into_overview, snap);
}

void OverviewSession::MergeWindowIntoOverviewForWebUITabStrip(
    aura::Window* dragged_window) {
  OverviewGrid* target_grid =
      GetGridWithRootWindow(dragged_window->GetRootWindow());
  if (!target_grid)
    return;
  target_grid->MergeWindowIntoOverviewForWebUITabStrip(dragged_window);
}

void OverviewSession::SetVisibleDuringWindowDragging(bool visible,
                                                     bool animate) {
  for (auto& grid : grid_list_)
    grid->SetVisibleDuringWindowDragging(visible, animate);
}

void OverviewSession::PositionWindows(
    bool animate,
    const base::flat_set<OverviewItemBase*>& ignored_items) {
  for (std::unique_ptr<OverviewGrid>& grid : grid_list_)
    grid->PositionWindows(animate, ignored_items);

  UpdateNoWindowsWidgetOnEachGrid(animate, /*is_continuous_enter=*/false);
}

bool OverviewSession::IsWindowInOverview(const aura::Window* window) {
  for (const std::unique_ptr<OverviewGrid>& grid : grid_list_) {
    if (grid->GetOverviewItemContaining(window))
      return true;
  }
  return false;
}

OverviewItemBase* OverviewSession::GetOverviewItemForWindow(
    const aura::Window* window) {
  for (const std::unique_ptr<OverviewGrid>& grid : grid_list_) {
    if (OverviewItemBase* item = grid->GetOverviewItemContaining(window)) {
      return item;
    }
  }

  return nullptr;
}

void OverviewSession::SetWindowListNotAnimatedWhenExiting(
    aura::Window* root_window) {
  // Find the grid accociated with |root_window|.
  OverviewGrid* grid = GetGridWithRootWindow(root_window);
  if (grid)
    grid->SetWindowListNotAnimatedWhenExiting();
}

void OverviewSession::UpdateRoundedCornersAndShadow() {
  for (auto& grid : grid_list_)
    for (auto& item : grid->item_list()) {
      item->UpdateRoundedCornersAndShadow();
    }
}

void OverviewSession::OnStartingAnimationComplete(bool canceled,
                                                  bool should_focus_overview) {
  for (auto& grid : grid_list_)
    grid->OnStartingAnimationComplete(canceled);

  if (canceled)
    return;

  if (overview_focus_widget_) {
    if (should_focus_overview) {
      overview_focus_widget_->Show();
    } else {
      overview_focus_widget_->ShowInactive();

      // Check if the active window is in overview. There is at least one
      // workflow where it will be: the active window is being dragged, and the
      // previous window carries over from clamshell mode to tablet split view.
      if (IsWindowInOverview(window_util::GetActiveWindow()) &&
          SplitViewController::Get(Shell::GetPrimaryRootWindow())
              ->InSplitViewMode()) {
        // We do not want an active window in overview. It will cause blatantly
        // broken behavior as in the video linked in crbug.com/992223.
        wm::ActivateWindow(
            SplitViewController::Get(Shell::GetPrimaryRootWindow())
                ->GetDefaultSnappedWindow());
      }
    }
  }

  UpdateAccessibilityFocus();
  OverviewController::Get()->DelayedUpdateRoundedCornersAndShadow();

  // The stacker object may be already created if a drag has started prior to
  // this.
  if (!float_container_stacker_) {
    float_container_stacker_ = std::make_unique<ScopedFloatContainerStacker>();
  }
}

void OverviewSession::OnWindowActivating(
    wm::ActivationChangeObserver::ActivationReason reason,
    aura::Window* gained_active,
    aura::Window* lost_active) {
  if (ignore_activations_ || gained_active == GetOverviewFocusWindow())
    return;

  // Activating any UI created for overview should not end overview.
  if (gained_active && gained_active->GetProperty(kOverviewUiKey)) {
    return;
  }

  // In addition to activation, overview UI that are losing activation due to
  // the window being destroyed should not end overview.
  if (lost_active && lost_active->GetProperty(kOverviewUiKey) &&
      lost_active->is_destroying()) {
    return;
  }

  // If the window should be ignored for activation changes, i.e.
  // SplitViewDivider, do not end overview.
  if (lost_active && lost_active->GetProperty(kIgnoreWindowActivationKey)) {
    return;
  }

  if (gained_active &&
      gained_active->GetProperty(kStayInOverviewOnActivationKey)) {
    return;
  }

  if (DesksController::Get()->AreDesksBeingModified()) {
    // Activating a desk from its mini view will activate its most-recently used
    // window, but this should not result in ending overview mode now.
    // Overview will be ended explicitly as part of the desk activation
    // animation.
    return;
  }

  if (!gained_active) {
    // Cancel overview session and do not restore activation when active window
    // is set to nullptr. This happens when removing a display.
    RestoreWindowActivation(false);
    EndOverview(OverviewEndAction::kWindowDeactivating);
    return;
  }

  // If app list is open in clamshell mode, end overview. Note: we have special
  // logic to end overview when app list (i.e., home launcher) is open in tablet
  // mode, so do not handle it here.
  if (gained_active == Shell::Get()->app_list_controller()->GetWindow() &&
      !display::Screen::GetScreen()->InTabletMode()) {
    RestoreWindowActivation(false);
    EndOverview(OverviewEndAction::kAppListActivatedInClamshell);
    return;
  }

  if (RootWindowController::ForWindow(gained_active)
          ->split_view_overview_session()) {
    // Let `SplitViewOverviewSession` handle the window activation change.
    RestoreWindowActivation(false);
    return;
  }

  // Do not cancel overview mode if the window activation happens when split
  // view mode is also active. SplitViewController will do the right thing to
  // handle the window activation change. Check for split view mode without
  // using |SplitViewController::state_| which is updated asynchronously when
  // snapping an ARC window.
  // We also check if `gained_active` is to-be-snapped transitional state. In
  // the case, the window has not been attached to SplitViewController yet but
  // will be very soon.
  SplitViewController* split_view_controller =
      SplitViewController::Get(gained_active);
  if (split_view_controller->primary_window() ||
      split_view_controller->secondary_window() ||
      split_view_controller->IsWindowInTransitionalState(gained_active)) {
    RestoreWindowActivation(false);
    return;
  }

  // Do not cancel overview mode while a window or overview item is being
  // dragged as evidenced by the presence of a drop target. (Dragging to close
  // does not count; canceling overview mode is okay then.)
  for (std::unique_ptr<OverviewGrid>& overview_grid : grid_list_) {
    if (overview_grid->drop_target()) {
      return;
    }
  }

  auto* grid = GetGridWithRootWindow(gained_active->GetRootWindow());
  DCHECK(grid);
  if (OverviewItemBase* item = grid->GetOverviewItemContaining(gained_active)) {
    selected_item_ = item;
  }

  // Don't restore window activation on exit if a window was just activated.
  RestoreWindowActivation(false);
  EndOverview(OverviewEndAction::kWindowActivating);
}

bool OverviewSession::IsSavedDeskUiLosingActivation(aura::Window* lost_active) {
  if (!lost_active || !saved_desk_util::ShouldShowSavedDesksOptions()) {
    return false;
  }

  for (auto& grid : grid_list_) {
    auto* desk_library_view = grid->GetSavedDeskLibraryView();
    if (desk_library_view &&
        lost_active == desk_library_view->GetWidget()->GetNativeWindow()) {
      return true;
    }
  }

  return saved_desk_dialog_controller_ &&
         saved_desk_dialog_controller_->dialog_widget() &&
         saved_desk_dialog_controller_->dialog_widget()->GetNativeWindow() ==
             lost_active;
}

aura::Window* OverviewSession::GetOverviewFocusWindow() const {
  return overview_focus_widget_ ? overview_focus_widget_->GetNativeWindow()
                                : nullptr;
}

aura::Window* OverviewSession::GetFocusedWindow() {
  auto* item_view = views::AsViewClass<OverviewItemView>(
      focus_cycler_.GetOverviewFocusedView());
  if (!item_view) {
    return nullptr;
  }

  OverviewItemBase* item = item_view->overview_item();
  return item ? item->GetWindow() : nullptr;
}

void OverviewSession::SuspendReposition() {
  for (auto& grid : grid_list_)
    grid->set_suspend_reposition(true);
}

void OverviewSession::ResumeReposition() {
  for (auto& grid : grid_list_)
    grid->set_suspend_reposition(false);
}

bool OverviewSession::IsEmpty() const {
  for (const auto& grid : grid_list_) {
    if (!grid->empty())
      return false;
  }
  return true;
}

void OverviewSession::RestoreWindowActivation(bool restore) {
  TRACE_EVENT0("ui", "OverviewSession::RestoreWindowActivation");

  if (!active_window_before_overview_)
    return;

  // Do not restore focus to a window that exists on an inactive desk.
  restore &= base::Contains(DesksController::Get()->active_desk()->windows(),
                            active_window_before_overview_);

  // Ensure the window is still in the window hierarchy and not in the middle
  // of teardown.
  if (restore && active_window_before_overview_->GetRootWindow()) {
    base::AutoReset<bool> restoring_focus(&ignore_activations_, true);
    wm::ActivateWindow(active_window_before_overview_);
  }
  active_window_before_overview_observation_.Reset();
  active_window_before_overview_ = nullptr;
}

void OverviewSession::OnFocusedItemActivated(OverviewItem* item) {
  UMA_HISTOGRAM_COUNTS_100("Ash.Overview.ArrowKeyPresses", num_key_presses_);

  // Do not record this if `num_start_windows_` has changed as it will be
  // inaccurate.
  if (num_start_windows_ == GetNumWindows()) {
    UMA_HISTOGRAM_CUSTOM_COUNTS("Ash.Overview.KeyPressesOverItemsRatio",
                                (num_key_presses_ * 100) / num_start_windows_,
                                1, 300, 30);
  }
  base::RecordAction(
      base::UserMetricsAction("WindowSelector_OverviewEnterKey"));
  SelectWindow(item);
}

void OverviewSession::OnFocusedItemClosed(OverviewItem* item) {
  base::RecordAction(
      base::UserMetricsAction("WindowSelector_OverviewCloseKey"));

  item->CloseWindow();
}

void OverviewSession::OnRootWindowClosing(aura::Window* root) {
  auto iter = base::ranges::find_if(
      grid_list_, [root](const std::unique_ptr<OverviewGrid>& grid) {
        return grid->root_window() == root;
      });
  DCHECK(iter != grid_list_.end());
  (*iter)->Shutdown(OverviewEnterExitType::kImmediateExit);
  grid_list_.erase(iter);
}

OverviewItemBase* OverviewSession::GetCurrentDraggedOverviewItem() const {
  return window_drag_controller_ ? window_drag_controller_->item() : nullptr;
}

bool OverviewSession::CanProcessEvent() const {
  return CanProcessEvent(/*sender=*/nullptr, /*from_touch_gesture=*/false);
}

bool OverviewSession::CanProcessEvent(OverviewItemBase* sender,
                                      bool from_touch_gesture) const {
  // Allow processing the event if no current window is being dragged.
  const bool drag_in_progress = window_util::IsAnyWindowDragged();
  if (!drag_in_progress)
    return true;

  // At this point, if there is no sender, we can't process the event since
  // |drag_in_progress| will be true.
  if (!sender || !window_drag_controller_)
    return false;

  // Allow processing the event if the sender is the one currently being
  // dragged and the event is the same type as the current one.
  if (sender == window_drag_controller_->item() &&
      from_touch_gesture == window_drag_controller_->is_touch_dragging()) {
    return true;
  }

  return false;
}

bool OverviewSession::IsWindowActiveWindowBeforeOverview(
    aura::Window* window) const {
  DCHECK(window);
  return window == active_window_before_overview_;
}

bool OverviewSession::HandleContinuousScrollIntoOverview(float y_offset) {
  if (OverviewController::Get()->is_continuous_scroll_in_progress()) {
    CHECK_EQ(enter_exit_overview_type_,
             OverviewEnterExitType::kContinuousAnimationEnterOnScrollUpdate);

    // If a scroll is in progress, position the windows continuously.
    for (std::unique_ptr<OverviewGrid>& overview_grid : grid_list_) {
      overview_grid->PositionWindowsContinuously(y_offset);
    }
    return true;
  }

  // If a scroll has ended, reset the opacity of minimized windows before
  // animating all windows into their final positions.
  for (std::unique_ptr<OverviewGrid>& overview_grid : grid_list_) {
    for (const auto& window_item : overview_grid->item_list()) {
      window_item->item_widget()->GetLayer()->SetOpacity(1.f);
      window_item->UpdateRoundedCornersAndShadow();
    }
    overview_grid->PositionWindows(/*animate=*/true, /*ignored_items=*/{},
                                   /*transition=*/OverviewTransition::kEnter);

    // TODO(http://b/292125336): Animate the desk bar transformation and no
    // windows label opacity.
    if (auto* desks_bar = overview_grid->desks_bar_view()) {
      desks_bar->layer()->SetTransform({});
    }

    if (auto* no_windows_widget = overview_grid->no_windows_widget()) {
      no_windows_widget->SetOpacity(1.f);
    }
  }
  return true;
}

void OverviewSession::ShowSavedDeskLibrary(
    const base::Uuid& item_to_focus,
    const std::u16string& saved_desk_name,
    aura::Window* const root_window) {
  // Some windows such as the print preview may request activation due to
  // occlusion computations. These should not cause use to exit overview.
  base::AutoReset<bool> ignore(&ignore_activations_, true);

  if (display::Screen::GetScreen()->InTabletMode() ||
      IsShowingSavedDeskLibrary()) {
    return;
  }

  const bool created_grid_widgets =
      !grid_list_.front()->GetSavedDeskLibraryView();

  // Send an a11y alert.
  Shell::Get()->accessibility_controller()->TriggerAccessibilityAlert(
      AccessibilityAlert::SAVED_DESKS_MODE_ENTERED);

  for (auto& grid : grid_list_)
    grid->ShowSavedDeskLibrary();

  // Only ask for all entries if it is the first time creating the grid widgets.
  // Otherwise, add or update the entries one at a time.
  if (created_grid_widgets) {
    saved_desk_presenter_->GetAllEntries(item_to_focus, saved_desk_name,
                                         root_window);
  }
  UpdateNoWindowsWidgetOnEachGrid(/*animate=*/true,
                                  /*is_continuous_enter=*/false);

  UpdateAccessibilityFocus();

  // If not given anything to focus, focus the first saved desk.
  if (item_to_focus.is_valid())
    return;

  OverviewGrid* overview_grid = GetGridWithRootWindow(root_window);
  if (!overview_grid)
    return;

  SavedDeskLibraryView* library_view = overview_grid->GetSavedDeskLibraryView();
  if (!library_view)
    return;

  std::vector<raw_ptr<SavedDeskGridView, VectorExperimental>> grid_views =
      library_view->grid_views();
  if (grid_views.empty())
    return;

  std::vector<raw_ptr<SavedDeskItemView, VectorExperimental>> grid_items =
      grid_views.front()->grid_items();
  if (grid_items.empty() ||
      library_view->GetWidget()->GetNativeWindow()->GetRootWindow() !=
          root_window) {
    return;
  }

  grid_items.front()->RequestFocus();
}

void OverviewSession::HideSavedDeskLibrary() {
  // Some windows such as the print preview may request activation due to
  // occlusion computations. These should not cause use to exit overview.
  base::AutoReset<bool> ignore(&ignore_activations_, true);

  for (auto& grid : grid_list_)
    grid->HideSavedDeskLibrary(/*exit_overview=*/false);

  UpdateAccessibilityFocus();
}

bool OverviewSession::IsShowingSavedDeskLibrary() const {
  // All the overview grids should show the saved desk grid at the same time so
  // just check if the first grid is showing.
  return grid_list_.empty() ? false
                            : grid_list_.front()->IsShowingSavedDeskLibrary();
}

bool OverviewSession::ShouldEnterWithoutAnimations() const {
  return enter_exit_overview_type_ == OverviewEnterExitType::kImmediateEnter ||
         enter_exit_overview_type_ ==
             OverviewEnterExitType::kImmediateEnterWithoutFocus;
}

void OverviewSession::UpdateAccessibilityFocus() {
  if (is_shutting_down()) {
    return;
  }

  focus_cycler_.UpdateAccessibilityFocus();
}

void OverviewSession::UpdateFrameThrottling() {
  std::vector<raw_ptr<aura::Window, VectorExperimental>> windows_to_throttle;
  if (!grid_list_.empty()) {
    windows_to_throttle.reserve(num_start_windows_ * 2);
    for (auto& grid : grid_list_) {
      if (grid->dragged_window()) {
        windows_to_throttle.push_back(grid->dragged_window());
      }

      for (auto& item : grid->item_list()) {
        for (aura::Window* window : item->GetWindows()) {
          windows_to_throttle.push_back(window);
        }
      }
    }
  }
  Shell::Get()->frame_throttling_controller()->StartThrottling(
      windows_to_throttle);
}

base::WeakPtr<OverviewSession> OverviewSession::GetWeakPtr() {
  return weak_ptr_factory_.GetWeakPtr();
}

void OverviewSession::OnDeskActivationChanged(const Desk* activated,
                                              const Desk* deactivated) {
  observing_desk_ = activated;

  for (aura::Window* root : Shell::GetAllRootWindows()) {
    activated->GetDeskContainerForRoot(root)->AddObserver(this);
    deactivated->GetDeskContainerForRoot(root)->RemoveObserver(this);

    if (auto* overview_grid = GetGridWithRootWindow(root))
      overview_grid->UpdateSaveDeskButtons();
  }
}

void OverviewSession::OnDisplayAdded(const display::Display& display) {
  if (EndOverview(OverviewEndAction::kDisplayAdded))
    return;
  SplitViewController::Get(Shell::GetPrimaryRootWindow())->EndSplitView();
  EndOverview(OverviewEndAction::kDisplayAdded);
}

void OverviewSession::OnDisplayMetricsChanged(const display::Display& display,
                                              uint32_t metrics) {
  // End the current drag if the display changes.
  if (window_drag_controller_ && window_drag_controller_->item()) {
    ResetDraggedWindowGesture();
  }

  auto* overview_grid =
      GetGridWithRootWindow(Shell::GetRootWindowForDisplayId(display.id()));
  overview_grid->OnDisplayMetricsChanged(metrics);

  // In case of split view mode, the no windows widget bounds will be updated in
  // |OnSplitViewDividerPositionChanged|.
  if (SplitViewController::Get(Shell::GetPrimaryRootWindow())
          ->InSplitViewMode()) {
    return;
  }
  overview_grid->UpdateNoWindowsWidget(IsEmpty(), /*animate=*/false,
                                       /*is_continuous_enter=*/false);
}

void OverviewSession::OnWindowDestroying(aura::Window* window) {
  DCHECK_EQ(active_window_before_overview_, window);
  active_window_before_overview_observation_.Reset();
  active_window_before_overview_ = nullptr;
}

void OverviewSession::OnWindowAdded(aura::Window* new_window) {
  if (!auto_add_windows_enabled_)
    return;

  // We track if we are in the process of adding an item to avoid recursively
  // adding items.
  if (is_adding_new_item_)
    return;
  base::AutoReset<bool> adding_new_item_resetter(&is_adding_new_item_, true);

  // If `new_window` belongs to Snap Group, wait until both windows are in the
  // desk container (handled by `SnapGroup::OnWindowParentChanged()`) before
  // adding the corresponding `OverviewGroupItem`.
  if (SnapGroupController* snap_group_controller = SnapGroupController::Get()) {
    if (SnapGroup* snap_group =
            snap_group_controller->GetSnapGroupForGivenWindow(new_window)) {
      if (snap_group->window1()->parent() != snap_group->window2()->parent()) {
        return;
      }
    }
  }

  // Avoid adding overview items for certain windows.
  if (!WindowState::Get(new_window) ||
      window_util::ShouldExcludeForOverview(new_window)) {
    return;
  }

  AddItemInMruOrder(new_window, /*reposition=*/true, /*animate=*/true,
                    /*restack=*/false, /*use_spawn_animation=*/true);

  // If a window is added from desk templates, we no longer want to go back to
  // the previous active window we had before entering overview, otherwise we
  // may activate a window and break the stacking order that the saved desk had.
  active_window_before_overview_observation_.Reset();
  active_window_before_overview_ = nullptr;
}

void OverviewSession::OnMouseEvent(ui::MouseEvent* event) {
  MaybeDelegateEventToSplitViewOverviewSession(event);
}

void OverviewSession::OnTouchEvent(ui::TouchEvent* event) {
  MaybeDelegateEventToSplitViewOverviewSession(event);
}

void OverviewSession::OnKeyEvent(ui::KeyEvent* event) {
  // If app list is open when overview is active (it can happen in clamshell
  // mode, when we snap an overview window to one side of the screen and then
  // open the app list to select an app to snap to the other side), in this case
  // we let the app list to handle the key event.
  // TODO(crbug.com/40622922): Explore better ways to handle this splitview +
  // overview + applist case.
  if (!display::Screen::GetScreen()->InTabletMode() &&
      Shell::Get()->app_list_controller()->IsVisible()) {
    return;
  }

  // If a desk templates dialog is visible it should receive the key events.
  if (saved_desk_dialog_controller_ &&
      saved_desk_dialog_controller_->dialog_widget()) {
    return;
  }

  if (TabAppSelectionHost* coral_selector =
          birch_bar_util::GetVisibleTabAppSelectionHost()) {
    coral_selector->ProcessKeyEvent(event);
    return;
  }

  // Check if we can scroll with the event first as it can use release events as
  // well.
  if (ProcessForScrolling(*event)) {
    event->SetHandled();
    event->StopPropagation();
    return;
  }

  if (event->type() != ui::EventType::kKeyPressed) {
    return;
  }

  const bool is_control_down = event->IsControlDown();
  const bool is_command_down = event->IsCommandDown();

  const ui::KeyboardCode key_code = event->key_code();
  switch (key_code) {
    case ui::VKEY_BROWSER_BACK:
    case ui::VKEY_ESCAPE: {
      // Let the textfield handle back and escape.
      views::View* focused_view = focus_cycler_.GetOverviewFocusedView();
      if (focused_view && views::IsViewClass<DeskTextfield>(focused_view)) {
        return;
      }
      EndOverview(OverviewEndAction::kKeyEscapeOrBack);
      break;
    }
    case ui::VKEY_UP:
    case ui::VKEY_DOWN: {
      ++num_key_presses_;
      Move(/*reverse=*/key_code == ui::VKEY_UP);
      break;
    }
    case ui::VKEY_LEFT:
    case ui::VKEY_RIGHT: {
      ++num_key_presses_;

      // Control + left/right falls through to be handed by the desk preview
      // to swap desks.
      if (is_control_down) {
        return;
      }

      // Let the textfield handle left/right to move the caret, unless using
      // ChromeVox traversal.
      views::View* focused_view = focus_cycler_.GetOverviewFocusedView();
      if (!is_command_down && focused_view &&
          views::IsViewClass<DeskTextfield>(focused_view)) {
        return;
      }

      Move(/*reverse=*/key_code == ui::VKEY_LEFT);
      break;
    }
    case ui::VKEY_TAB: {
      const bool reverse = event->IsShiftDown();
      ++num_key_presses_;
      Move(reverse);
      break;
    }
    case ui::VKEY_Z: {
      // Ctrl + Z undos a close all operation if the toast has not yet expired.
      // Ctrl + Alt + Z triggers ChromeVox so we don't do anything here to
      // interrupt that.
      if (!is_control_down || (is_control_down && event->IsAltDown())) {
        return;
      }

      DesksController::Get()->MaybeCancelDeskRemoval();
      break;
    }
    case ui::VKEY_RETURN:
    case ui::VKEY_SPACE: {
      return;
    }
    default: {
      // Window activation change happens after overview start animation is
      // finished for performance reasons. During the animation, the focused
      // window prior to entering overview still has focus so stop events from
      // reaching it. See https://crbug.com/951324 for more details.
      if (OverviewController::Get()->IsInStartAnimation()) {
        break;
      }

      return;
    }
  }

  event->SetHandled();
  event->StopPropagation();
}

void OverviewSession::OnShellDestroying() {
  // Cancel selection will call |Shutdown()|, which will remove observer.
  EndOverview(OverviewEndAction::kShuttingDown);
}

void OverviewSession::OnShelfAlignmentChanged(aura::Window* root_window,
                                              ShelfAlignment old_alignment) {
  // Helper to check if a shelf alignment change results in different
  // visuals for overivew purposes.
  auto same_effective_alignment = [](ShelfAlignment prev,
                                     ShelfAlignment curr) -> bool {
    auto bottom = ShelfAlignment::kBottom;
    auto locked = ShelfAlignment::kBottomLocked;
    return (prev == bottom && curr == locked) ||
           (prev == locked && curr == bottom);
  };

  // On changing from kBottomLocked to kBottom shelf alignment or vice versa
  // (usually from entering/exiting lock screen), keep splitview if it's active.
  // Done here instead of using a SessionObserver so we can skip the
  // EndOverview() at the end of this function if necessary.
  ShelfAlignment current_alignment = Shelf::ForWindow(root_window)->alignment();
  if (SplitViewController::Get(root_window)->InSplitViewMode() &&
      same_effective_alignment(old_alignment, current_alignment)) {
    return;
  }

  // When the shelf alignment changes while in overview, the display work area
  // doesn't get updated anyways (see https://crbug.com/834400). In this case,
  // even updating the grid bounds won't make any difference, so we simply exit
  // overview.
  EndOverview(OverviewEndAction::kShelfAlignmentChanged);
}

void OverviewSession::OnUserWorkAreaInsetsChanged(aura::Window* root_window) {
  // Don't make any change if |root_window| is not the primary root window.
  // Because ChromveVox is only shown on the primary window.
  if (root_window != Shell::GetPrimaryRootWindow())
    return;

  const bool new_chromevox_enabled =
      Shell::Get()->accessibility_controller()->spoken_feedback().enabled();
  // Don't make any change if ChromeVox status remains the same.
  if (new_chromevox_enabled == chromevox_enabled_)
    return;

  // Make ChromeVox status up to date.
  chromevox_enabled_ = new_chromevox_enabled;

  for (std::unique_ptr<OverviewGrid>& overview_grid : grid_list_) {
    // Do not handle work area insets change in |overview_grid| if its root
    // window doesn't match |root_window|.
    if (root_window == overview_grid->root_window())
      overview_grid->OnUserWorkAreaInsetsChanged(root_window);
  }
}

void OverviewSession::OnSplitViewStateChanged(
    SplitViewController::State previous_state,
    SplitViewController::State state) {
  // Do nothing if overview is being shutdown.
  if (!OverviewController::Get()->InOverviewSession()) {
    return;
  }

  // Entering or exiting splitview is unexpected behavior in an informed restore
  // overview session.
  if (features::IsForestFeatureEnabled()) {
    CHECK(!Shell::Get()->informed_restore_controller()->contents_data());
  }

  UpdateNoWindowsWidgetOnEachGrid(/*animate=*/false,
                                  /*is_continuous_enter=*/false);
}

void OverviewSession::OnSplitViewDividerPositionChanged() {
  UpdateNoWindowsWidgetOnEachGrid(/*animate=*/false,
                                  /*is_continuous_enter=*/false);
}

void OverviewSession::OnSnapGroupRemoving(SnapGroup* snap_group,
                                          SnapGroupExitPoint exit_pint) {
  if (is_shutting_down_) {
    return;
  }

  // Return early if `snap_group` removal is due to window destruction, as
  // `OverviewItem::window_destruction_delegate_` will handle it.
  if (exit_pint == SnapGroupExitPoint::kWindowDestruction) {
    return;
  }

  CHECK(snap_group);

  aura::Window* root_window = snap_group->GetRootWindow();
  OverviewGrid* overview_grid = GetGridWithRootWindow(root_window);
  aura::Window* window1 = snap_group->window1();
  aura::Window* window2 = snap_group->window2();

  OverviewItemBase* overview_group_item = GetOverviewItemForWindow(window1);
  if (!overview_group_item) {
    base::debug::DumpWithoutCrashing();
    return;
  }

  overview_grid->RemoveItem(overview_group_item, /*item_destroying=*/false,
                            /*reposition=*/false);

  for (aura::Window* window : {window1, window2}) {
    CHECK(window);
    if (GetOverviewItemForWindow(window)) {
      base::debug::DumpWithoutCrashing();
      continue;
    }

    overview_grid->AddItemInMruOrder(window, /*reposition=*/false,
                                     /*animate=*/true, /*restack=*/true,
                                     /*use_spawn_animation=*/true);
  }
}

void OverviewSession::OnDisplayTabletStateChanged(display::TabletState state) {
  if (window_drag_controller_ && window_drag_controller_->item()) {
    // End the current drag on tablet state changes.
    ResetDraggedWindowGesture();
  }

  if (display::IsTabletStateChanging(state)) {
    // Do nothing if the tablet state is still in the process of transition.
    return;
  }

  OnTabletModeChanged();
}

void OverviewSession::OnTabletModeChanged() {
  for (auto& overview_grid : grid_list_) {
    overview_grid->OnTabletModeChanged();
  }

  // `saved_desk_presenter_` could be null if we started overview during a guest
  // session.
  if (saved_desk_presenter_) {
    saved_desk_presenter_->UpdateUIForSavedDeskLibrary();
  }
}

void OverviewSession::Move(bool reverse) {
  // Do not allow moving the focus ring while in the middle of a drag.
  if (window_util::IsAnyWindowDragged() || desks_util::IsDraggingAnyDesk()) {
    return;
  }

  focus_cycler_.MoveFocus(reverse);
}

bool OverviewSession::ProcessForScrolling(const ui::KeyEvent& event) {
  if (!display::Screen::GetScreen()->InTabletMode()) {
    return false;
  }

  // The scrollable overview grid only works for tablet mode, so using the
  // primary display works.
  auto* grid = GetGridWithRootWindow(Shell::GetPrimaryRootWindow());
  const bool press = (event.type() == ui::EventType::kKeyPressed);

  if (!press) {
    if (is_keyboard_scrolling_grid_) {
      is_keyboard_scrolling_grid_ = false;
      grid->EndScroll();
      return true;
    }
    return false;
  }

  // Presses only at this point.
  if (event.key_code() != ui::VKEY_LEFT && event.key_code() != ui::VKEY_RIGHT)
    return false;

  if (!event.IsControlDown())
    return false;

  const bool repeat = event.is_repeat();
  const bool reverse = event.key_code() == ui::VKEY_LEFT;
  if (!repeat) {
    is_keyboard_scrolling_grid_ = true;
    grid->StartScroll();
    grid->UpdateScrollOffset(kKeyboardPressScrollingDp * (reverse ? 1 : -1));
    return true;
  }

  grid->UpdateScrollOffset(kKeyboardHoldScrollingDp * (reverse ? 1 : -1));
  return true;
}

void OverviewSession::RemoveAllObservers() {
  display_observer_.reset();
  active_window_before_overview_observation_.Reset();
  active_window_before_overview_ = nullptr;
}

void OverviewSession::UpdateNoWindowsWidgetOnEachGrid(
    bool animate,
    bool is_continuous_enter) {
  if (is_shutting_down_)
    return;

  for (auto& grid : grid_list_) {
    grid->UpdateNoWindowsWidget(IsEmpty(), animate, is_continuous_enter);
  }
}

void OverviewSession::OnItemAdded(aura::Window* window) {
  UpdateNoWindowsWidgetOnEachGrid(/*animate=*/true,
                                  /*is_continuous_enter=*/false);

  // Transfer focus from `window` to `overview_focus_widget_` to match the
  // behavior of entering overview mode in the beginning.
  DCHECK(overview_focus_widget_);
  // `overview_focus_widget_` might not visible yet as `OnItemAdded()` might be
  // called before `OnStartingAnimationComplete()` is called, so use `Show()` or
  // `ShowInactive()` instead of `ActivateWindow()` to show the widget.
  // When the saved desk library is on, do not switch focus to avoid unexpected
  // name commit.
  bool saved_desk_grid_should_keep_focus = IsShowingSavedDeskLibrary();
  if (saved_desk_grid_should_keep_focus)
    overview_focus_widget_->ShowInactive();
  else
    overview_focus_widget_->Show();

  UpdateAccessibilityFocus();
}

size_t OverviewSession::GetNumWindows() const {
  size_t size = 0u;
  for (const std::unique_ptr<OverviewGrid>& grid : grid_list_) {
    size += grid->GetNumWindows();
  }
  return size;
}

void OverviewSession::MaybeDelegateEventToSplitViewOverviewSession(
    ui::LocatedEvent* event) {
  for (auto& grid : grid_list_) {
    if (auto* split_view_overview_session =
            RootWindowController::ForWindow(grid->root_window())
                ->split_view_overview_session();
        split_view_overview_session) {
      split_view_overview_session->HandleClickOrTap(*event);
      return;
    }
  }
}

}  // namespace ash