Refactor MediaSourceDelegate destruction.

This CL introduces a waiter in ~WebMediaPlayerAndroid() and makes sure objects
are destructed after MediaSourceDelegate is completly stopped.

BUG=417864

Review URL: https://codereview.chromium.org/605013002

Cr-Commit-Position: refs/heads/master@{#297031}

content/renderer/media/android/media_source_delegate.cc

@@ -81,13 +81,12 @@ MediaSourceDelegate::~MediaSourceDelegate() {
   DCHECK(!video_stream_);
 }
 
-void MediaSourceDelegate::Destroy() {
+void MediaSourceDelegate::Stop(const base::Closure& stop_cb) {
   DCHECK(main_task_runner_->BelongsToCurrentThread());
   DVLOG(1) << __FUNCTION__ << " : " << demuxer_client_id_;
 
   if (!chunk_demuxer_) {
     DCHECK(!demuxer_client_);
-    delete this;
     return;
   }
 
@@ -100,12 +99,11 @@ void MediaSourceDelegate::Destroy() {
 
   chunk_demuxer_->Shutdown();
 
-  // |this| will be transferred to the callback StopDemuxer() and
-  // OnDemuxerStopDone(). They own |this| and OnDemuxerStopDone() will delete
-  // it when called, hence using base::Unretained(this) is safe here.
-  media_task_runner_->PostTask(FROM_HERE,
-                        base::Bind(&MediaSourceDelegate::StopDemuxer,
-                        base::Unretained(this)));
+  // Continue to stop objects on the media thread.
+  media_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(
+          &MediaSourceDelegate::StopDemuxer, base::Unretained(this), stop_cb));
 }
 
 bool MediaSourceDelegate::IsVideoEncrypted() {
@@ -122,7 +120,8 @@ base::Time MediaSourceDelegate::GetTimelineOffset() const {
   return chunk_demuxer_->GetTimelineOffset();
 }
 
-void MediaSourceDelegate::StopDemuxer() {
+void MediaSourceDelegate::StopDemuxer(const base::Closure& stop_cb) {
+  DVLOG(2) << __FUNCTION__;
   DCHECK(media_task_runner_->BelongsToCurrentThread());
   DCHECK(chunk_demuxer_);
 
@@ -142,11 +141,9 @@ void MediaSourceDelegate::StopDemuxer() {
   chunk_demuxer_->Stop();
   chunk_demuxer_.reset();
 
-  // The callback DeleteSelf() owns |this| and will delete it when called.
-  // Hence using base::Unretained(this) is safe here.
-  media_task_runner_->PostTask(
-      FROM_HERE,
-      base::Bind(&MediaSourceDelegate::DeleteSelf, base::Unretained(this)));
+  // |this| may be destroyed at this point in time as a result of running
+  // |stop_cb|.
+  stop_cb.Run();
 }
 
 void MediaSourceDelegate::InitializeMediaSource(
@@ -630,12 +627,6 @@ void MediaSourceDelegate::FinishResettingDecryptingDemuxerStreams() {
   demuxer_client_->DemuxerSeekDone(demuxer_client_id_, browser_seek_time_);
 }
 
-void MediaSourceDelegate::DeleteSelf() {
-  DCHECK(main_task_runner_->BelongsToCurrentThread());
-  DVLOG(1) << __FUNCTION__ << " : " << demuxer_client_id_;
-  delete this;
-}
-
 void MediaSourceDelegate::NotifyDemuxerReady() {
   DCHECK(media_task_runner_->BelongsToCurrentThread());
   DVLOG(1) << __FUNCTION__ << " : " << demuxer_client_id_;

content/renderer/media/android/media_source_delegate.h

@@ -47,20 +47,12 @@ class MediaSourceDelegate : public media::DemuxerHost {
       UpdateNetworkStateCB;
   typedef base::Callback<void(const base::TimeDelta&)> DurationChangeCB;
 
-  // Helper class used by scoped_ptr to destroy an instance of
-  // MediaSourceDelegate.
-  class Destroyer {
-   public:
-    inline void operator()(void* media_source_delegate) const {
-      static_cast<MediaSourceDelegate*>(media_source_delegate)->Destroy();
-    }
-  };
-
   MediaSourceDelegate(
       RendererDemuxerAndroid* demuxer_client,
       int demuxer_client_id,
       const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
       const scoped_refptr<media::MediaLog> media_log);
+  virtual ~MediaSourceDelegate();
 
   // Initialize the MediaSourceDelegate. |media_source| will be owned by
   // this object after this call.
@@ -101,8 +93,8 @@ class MediaSourceDelegate : public media::DemuxerHost {
   // Called when DemuxerStreamPlayer needs to read data from ChunkDemuxer.
   void OnReadFromDemuxer(media::DemuxerStream::Type type);
 
-  // Called by the Destroyer to destroy an instance of this object.
-  void Destroy();
+  // Must be called explicitly before |this| can be destroyed.
+  void Stop(const base::Closure& stop_cb);
 
   // Called on the main thread to check whether the video stream is encrypted.
   bool IsVideoEncrypted();
@@ -111,9 +103,6 @@ class MediaSourceDelegate : public media::DemuxerHost {
   base::Time GetTimelineOffset() const;
 
  private:
-  // This is private to enforce use of the Destroyer.
-  virtual ~MediaSourceDelegate();
-
   // Methods inherited from DemuxerHost.
   virtual void AddBufferedTimeRange(base::TimeDelta start,
                                     base::TimeDelta end) OVERRIDE;
@@ -146,15 +135,14 @@ class MediaSourceDelegate : public media::DemuxerHost {
   void ResetVideoDecryptingDemuxerStream();
   void FinishResettingDecryptingDemuxerStreams();
 
-  // Helper for deleting |this| on the main thread.
-  void DeleteSelf();
-
   void OnDemuxerOpened();
   void OnNeedKey(const std::string& type,
                  const std::vector<uint8>& init_data);
   void NotifyDemuxerReady();
 
-  void StopDemuxer();
+  // Stops and clears objects on the media thread.
+  void StopDemuxer(const base::Closure& stop_cb);
+
   void InitializeDemuxer();
   void SeekInternal(const base::TimeDelta& seek_time);
   // Reads an access unit from the demuxer stream |stream| and stores it in

content/renderer/media/android/webmediaplayer_android.cc

@@ -210,6 +210,16 @@ WebMediaPlayerAndroid::~WebMediaPlayerAndroid() {
     delegate_->PlayerGone(this);
 
   stream_texture_factory_->RemoveObserver(this);
+
+  if (media_source_delegate_) {
+    // Part of |media_source_delegate_| needs to be stopped on the media thread.
+    // Wait until |media_source_delegate_| is fully stopped before tearing
+    // down other objects.
+    base::WaitableEvent waiter(false, false);
+    media_source_delegate_->Stop(
+        base::Bind(&base::WaitableEvent::Signal, base::Unretained(&waiter)));
+    waiter.Wait();
+  }
 }
 
 void WebMediaPlayerAndroid::load(LoadType load_type,

content/renderer/media/android/webmediaplayer_android.h

@@ -455,9 +455,6 @@ class WebMediaPlayerAndroid : public blink::WebMediaPlayer,
   bool force_use_overlay_embedded_video_;
 #endif  // defined(VIDEO_HOLE)
 
-  scoped_ptr<MediaSourceDelegate,
-             MediaSourceDelegate::Destroyer> media_source_delegate_;
-
   MediaPlayerHostMsg_Initialize_Type player_type_;
 
   // Whether the browser is currently connected to a remote media player.
@@ -503,6 +500,8 @@ class WebMediaPlayerAndroid : public blink::WebMediaPlayer,
   // as playback progresses.
   media::TimeDeltaInterpolator interpolator_;
 
+  scoped_ptr<MediaSourceDelegate> media_source_delegate_;
+
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<WebMediaPlayerAndroid> weak_factory_;