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content / browser / media / session / media_players_callback_aggregator.h [blame]
// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CONTENT_BROWSER_MEDIA_SESSION_MEDIA_PLAYERS_CALLBACK_AGGREGATOR_H_
#define CONTENT_BROWSER_MEDIA_SESSION_MEDIA_PLAYERS_CALLBACK_AGGREGATOR_H_
#include <memory>
#include "base/functional/callback.h"
#include "base/memory/ref_counted.h"
#include "content/common/content_export.h"
namespace content {
// This class is used by the `MediaSessionImpl` to aggregate multiple callbacks
// that are sent to the media player implementation on the renderer, as a result
// of a media session request.
//
// Once all callbacks are evaluated, or during callback evaluation (depending on
// method implementation), the `MediaPlayersCallbackAggregator` will reply to
// the browser with the final answer.
//
// In order to keep the aggregator alive, you must create the aggregator
// using scoped_refptr s, and bind the desired aggregator method using a strong
// reference. Once all callbacks sent to the renderer finish their execution,
// and if not already done, the aggregator will send a reply to the browser with
// the resulting aggregated value.
//
// Sample usage:
//
// // Create the aggregator, passing the callback that will be executed (if it
// is not null), once all tasks sent to the renderer finish executing.
// scoped_refptr<MediaPlayersCallbackAggregator> aggregator =
// MakeRefCounted<MediaPlayersCallbackAggregator>(std::move(callback));
//
// // Iterate through the desired players, creating the tasks that will be sent
// to the renderer.
// for (const auto player : normal_players_) {
// base::OnceCallback<void(bool)> task =
// aggregator->CreateVisibilityCallback();
// player.first.observer->OnRequestVisibility(player.first.player_id,
// std::move(task));
// }
class CONTENT_EXPORT MediaPlayersCallbackAggregator
: public base::RefCountedThreadSafe<MediaPlayersCallbackAggregator> {
public:
// Individual callbacks to ask the renderer for player's video visibility.
using VisibilityCb = base::OnceCallback<void(bool)>;
// Aggregate callback. Run once if any player returns `true` for
// `meets_visibility_threshold`, or at destruction time if no player returns
// `true` for `meets_visibility_threshold`.
using ReportVisibilityCb = base::OnceCallback<void(bool)>;
explicit MediaPlayersCallbackAggregator(
ReportVisibilityCb report_visibility_cb);
MediaPlayersCallbackAggregator() = delete;
MediaPlayersCallbackAggregator(const MediaPlayersCallbackAggregator&) =
delete;
MediaPlayersCallbackAggregator(MediaPlayersCallbackAggregator&&) = delete;
MediaPlayersCallbackAggregator& operator=(
const MediaPlayersCallbackAggregator&) = delete;
// Creates and returns a `VisibilityCb`. The resulting callback holds a strong
// reference to the aggregator, therefore it will live until all
// `VisibilityCb` s are executed.
VisibilityCb CreateVisibilityCallback();
private:
friend class base::RefCountedThreadSafe<MediaPlayersCallbackAggregator>;
~MediaPlayersCallbackAggregator();
void OnGetVisibility(bool meets_visibility_threshold);
ReportVisibilityCb report_visibility_cb_;
};
} // namespace content
#endif // CONTENT_BROWSER_MEDIA_SESSION_MEDIA_PLAYERS_CALLBACK_AGGREGATOR_H_