Bug 1633010 - part6 : use `IMediaController` if we only want to access control related methods r=chunmin

This patch will do :
- create an interface `IMediaController` including only control related methods

The advantage of doing so :
- It's clear to use `IMediaController` as the only surface to control media
- explictly restrict which functions are available which can avoid using control related functions on those situations

Differential Revision: https://phabricator.services.mozilla.com/D73490

dom/media/mediacontrol/AudioFocusManager.cpp

@@ -4,6 +4,7 @@
 
 #include "AudioFocusManager.h"
 
+#include "MediaController.h"
 #include "MediaControlUtils.h"
 #include "MediaControlService.h"
 #include "mozilla/dom/CanonicalBrowsingContext.h"
@@ -18,7 +19,7 @@
 namespace mozilla {
 namespace dom {
 
-void AudioFocusManager::RequestAudioFocus(MediaController* aController) {
+void AudioFocusManager::RequestAudioFocus(IMediaController* aController) {
   MOZ_ASSERT(aController);
   if (mOwningFocusControllers.Contains(aController)) {
     return;
@@ -28,7 +29,7 @@ void AudioFocusManager::RequestAudioFocus(MediaController* aController) {
   mOwningFocusControllers.AppendElement(aController);
 }
 
-void AudioFocusManager::RevokeAudioFocus(MediaController* aController) {
+void AudioFocusManager::RevokeAudioFocus(IMediaController* aController) {
   MOZ_ASSERT(aController);
   if (!mOwningFocusControllers.Contains(aController)) {
     return;

dom/media/mediacontrol/AudioFocusManager.h

@@ -11,7 +11,7 @@
 namespace mozilla {
 namespace dom {
 
-class MediaController;
+class IMediaController;
 class MediaControlService;
 
 /**
@@ -25,8 +25,8 @@ class MediaControlService;
  */
 class AudioFocusManager {
  public:
-  void RequestAudioFocus(MediaController* aController);
-  void RevokeAudioFocus(MediaController* aController);
+  void RequestAudioFocus(IMediaController* aController);
+  void RevokeAudioFocus(IMediaController* aController);
 
   explicit AudioFocusManager() = default;
   ~AudioFocusManager() = default;
@@ -37,7 +37,7 @@ class AudioFocusManager {
   friend class MediaControlService;
   void ClearFocusControllersIfNeeded();
 
-  nsTArray<RefPtr<MediaController>> mOwningFocusControllers;
+  nsTArray<RefPtr<IMediaController>> mOwningFocusControllers;
 };
 
 }  // namespace dom

dom/media/mediacontrol/MediaControlKeysEvent.cpp

@@ -32,7 +32,7 @@ void MediaControlKeysHandler::OnKeyPressed(MediaControlKeysEvent aKeyEvent) {
 
   RefPtr<MediaControlService> service = MediaControlService::GetService();
   MOZ_ASSERT(service);
-  RefPtr<MediaController> controller = service->GetMainController();
+  RefPtr<IMediaController> controller = service->GetMainController();
   if (!controller) {
     return;
   }
@@ -48,7 +48,7 @@ void MediaControlKeysHandler::OnKeyPressed(MediaControlKeysEvent aKeyEvent) {
       controller->Pause();
       return;
     case MediaControlKeysEvent::ePlayPause: {
-      if (controller->GetState() == MediaSessionPlaybackState::Playing) {
+      if (controller->IsPlaying()) {
         controller->Pause();
       } else {
         controller->Play();

dom/media/mediacontrol/MediaController.cpp

@@ -84,6 +84,12 @@ void MediaController::Stop() {
       MediaControlKeysEvent::eStop);
 }
 
+uint64_t MediaController::Id() const { return mTopLevelBCId; }
+
+bool MediaController::IsAudible() const { return IsMediaAudible(); }
+
+bool MediaController::IsPlaying() const { return IsMediaPlaying(); }
+
 void MediaController::UpdateMediaControlKeysEventToContentMediaIfNeeded(
     MediaControlKeysEvent aEvent) {
   // There is no controlled media existing or controller has been shutdown, we
@@ -98,7 +104,7 @@ void MediaController::UpdateMediaControlKeysEventToContentMediaIfNeeded(
   RefPtr<BrowsingContext> context =
       mActiveMediaSessionContextId
           ? BrowsingContext::Get(*mActiveMediaSessionContextId)
-          : BrowsingContext::Get(mTopLevelBCId);
+          : BrowsingContext::Get(Id());
   if (context && !context->IsDiscarded()) {
     context->Canonical()->UpdateMediaControlKeysEvent(aEvent);
   }
@@ -216,7 +222,5 @@ bool MediaController::IsInPictureInPictureMode() const {
   return mIsInPictureInPictureMode;
 }
 
-bool MediaController::IsAudible() const { return IsMediaAudible(); }
-
 }  // namespace dom
 }  // namespace mozilla

dom/media/mediacontrol/MediaController.h

@@ -21,6 +21,30 @@ namespace dom {
 class BrowsingContext;
 enum class MediaControlKeysEvent : uint32_t;
 
+/**
+ * IMediaController is an interface which includes control related methods and
+ * methods used to know its playback state.
+ */
+class IMediaController {
+ public:
+  NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING
+
+  // Focus the window currently playing media.
+  virtual void Focus() = 0;
+  virtual void Play() = 0;
+  virtual void Pause() = 0;
+  virtual void Stop() = 0;
+  virtual void PrevTrack() = 0;
+  virtual void NextTrack() = 0;
+  virtual void SeekBackward() = 0;
+  virtual void SeekForward() = 0;
+
+  // Return the ID of the top level browsing context within a tab.
+  virtual uint64_t Id() const = 0;
+  virtual bool IsAudible() const = 0;
+  virtual bool IsPlaying() const = 0;
+};
+
 /**
  * MediaController is a class, which is used to control all media within a tab.
  * It can only be used in Chrome process and the controlled media are usually
@@ -46,22 +70,26 @@ enum class MediaControlKeysEvent : uint32_t;
  * controller from `MediaControlService`.
  */
 class MediaController final
-    : public MediaSessionController,
+    : public IMediaController,
+      public MediaSessionController,
       public LinkedListElement<RefPtr<MediaController>> {
  public:
   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(MediaController, override);
 
   explicit MediaController(uint64_t aContextId);
 
-  // Focus the window currently playing media.
-  void Focus();
-  void Play();
-  void Pause();
-  void Stop();
-  void PrevTrack();
-  void NextTrack();
-  void SeekBackward();
-  void SeekForward();
+  // IMediaController's methods
+  void Focus() override;
+  void Play() override;
+  void Pause() override;
+  void Stop() override;
+  void PrevTrack() override;
+  void NextTrack() override;
+  void SeekBackward() override;
+  void SeekForward() override;
+  uint64_t Id() const override;
+  bool IsAudible() const override;
+  bool IsPlaying() const override;
 
   // IMediaInfoUpdater's methods
   void NotifyMediaPlaybackChanged(uint64_t aBrowsingContextId,
@@ -78,8 +106,6 @@ class MediaController final
   // then calling any its method won't take any effect.
   void Shutdown();
 
-  bool IsAudible() const;
-
  private:
   ~MediaController();
 

dom/media/mediasession/MediaSessionController.h

@@ -111,7 +111,6 @@ class MediaSessionController : public IMediaInfoUpdater {
   // it has already set its metadata. Otherwise, return default media metadata
   // which is based on website's title and favicon.
   MediaMetadataBase GetCurrentMediaMetadata() const;
-  uint64_t Id() const { return mTopLevelBCId; }
 
   bool IsMediaAudible() const;
   bool IsMediaPlaying() const;