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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at */
#include "mozilla/Maybe.h"
#include "mozilla/RefPtr.h"
#include "nsISupportsImpl.h"
#include "nsTArray.h"
#include "nsTHashMap.h"
namespace mozilla {
namespace dom {
* This enum is used to update controlled media state to the media controller in
* the chrome process.
* `eStarted`: media has successfully registered to the content media controller
* `ePlayed` : media has started playing
* `ePaused` : media has paused playing, but still can be resumed by content
* media controller
* `eStopped`: media has unregistered from the content media controller, we can
* not control it anymore
enum class MediaPlaybackState : uint32_t {
* This enum is used to update controlled media audible audible state to the
* media controller in the chrome process.
enum class MediaAudibleState : bool {
eInaudible = false,
eAudible = true,
* MediaPlaybackStatus is an internal module for the media controller, it
* represents a tab's media related status, such like "does the tab contain any
* controlled media? is the tab playing? is the tab audible?".
* The reason we need this class is that we would like to encapsulate the
* details of determining the tab's media status. A tab can contains multiple
* browsing contexts, and each browsing context can have different media status.
* The final media status would be decided by checking all those context status.
* Use `UpdateMediaXXXState()` to update controlled media status, and use
* `IsXXX()` methods to acquire the playback status of the tab.
* As we know each context's audible state, we can decide which context should
* owns the audio focus when multiple contexts are all playing audible media at
* the same time. In that cases, the latest context that plays media would own
* the audio focus. When the context owning the audio focus is destroyed, we
* would see if there is another other context still playing audible media, and
* switch the audio focus to another context.
class MediaPlaybackStatus final {
void UpdateMediaPlaybackState(uint64_t aContextId, MediaPlaybackState aState);
void UpdateMediaAudibleState(uint64_t aContextId, MediaAudibleState aState);
bool IsPlaying() const;
bool IsAudible() const;
bool IsAnyMediaBeingControlled() const;
Maybe<uint64_t> GetAudioFocusOwnerContextId() const;
* This internal class stores detailed media status of controlled media for
* a browsing context.
class ContextMediaInfo final {
explicit ContextMediaInfo(uint64_t aContextId) : mContextId(aContextId) {}
~ContextMediaInfo() = default;
void IncreaseControlledMediaNum() {
void DecreaseControlledMediaNum() {
MOZ_DIAGNOSTIC_ASSERT(mControlledMediaNum > 0);
void IncreasePlayingMediaNum() {
MOZ_DIAGNOSTIC_ASSERT(mPlayingMediaNum < mControlledMediaNum);
void DecreasePlayingMediaNum() {
MOZ_DIAGNOSTIC_ASSERT(mPlayingMediaNum > 0);
void IncreaseAudibleMediaNum() {
MOZ_DIAGNOSTIC_ASSERT(mAudibleMediaNum < mPlayingMediaNum);
void DecreaseAudibleMediaNum() {
MOZ_DIAGNOSTIC_ASSERT(mAudibleMediaNum > 0);
bool IsPlaying() const { return mPlayingMediaNum > 0; }
bool IsAudible() const { return mAudibleMediaNum > 0; }
bool IsAnyMediaBeingControlled() const { return mControlledMediaNum > 0; }
uint64_t Id() const { return mContextId; }
* The possible value for those three numbers should follow this rule,
* mControlledMediaNum >= mPlayingMediaNum >= mAudibleMediaNum
uint32_t mControlledMediaNum = 0;
uint32_t mAudibleMediaNum = 0;
uint32_t mPlayingMediaNum = 0;
uint64_t mContextId = 0;
ContextMediaInfo& GetNotNullContextInfo(uint64_t aContextId);
void DestroyContextInfo(uint64_t aContextId);
void ChooseNewContextToOwnAudioFocus();
void SetOwningAudioFocusContextId(Maybe<uint64_t>&& aContextId);
bool IsContextOwningAudioFocus(uint64_t aContextId) const;
bool ShouldRequestAudioFocusForInfo(const ContextMediaInfo& aInfo) const;
bool ShouldAbandonAudioFocusForInfo(const ContextMediaInfo& aInfo) const;
// This contains all the media status of browsing contexts within a tab.
nsTHashMap<uint64_t, UniquePtr<ContextMediaInfo>> mContextInfoMap;
Maybe<uint64_t> mOwningAudioFocusContextId;
} // namespace dom
} // namespace mozilla