Convert MediaLog from being ref counted to owned by WebMediaPlayer.

content/renderer/media/webmediaplayer_ms_compositor.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_RENDERER_MEDIA_WEBMEDIAPLAYER_MS_COMPOSITOR_H_
 #define CONTENT_RENDERER_MEDIA_WEBMEDIAPLAYER_MS_COMPOSITOR_H_
 
 #include <stddef.h>
 
 #include <map>
 #include <memory>
 #include <vector>
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread_checker.h"
 #include "cc/layers/video_frame_provider.h"
 #include "content/common/content_export.h"
+#include "media/base/media_log.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 }
 
 namespace blink {
 class WebMediaStream;
 }
 
 namespace gfx {
 class Size;
 }
 
 namespace media {
-class MediaLog;
 class VideoRendererAlgorithm;
 }
 
 namespace content {
 class WebMediaPlayerMS;
 
 // This class is designed to handle the work load on compositor thread for
 // WebMediaPlayerMS. It will be instantiated on the main thread, but destroyed
 // on the thread holding the last reference.
 //
 // WebMediaPlayerMSCompositor utilizes VideoRendererAlgorithm to store the
 // incoming frames and select the best frame for rendering to maximize the
 // smoothness, if REFERENCE_TIMEs are populated for incoming VideoFrames.
 // Otherwise, WebMediaPlayerMSCompositor will simply store the most recent
 // frame, and submit it whenever asked by the compositor.
 class CONTENT_EXPORT WebMediaPlayerMSCompositor
     : public NON_EXPORTED_BASE(cc::VideoFrameProvider),
       public base::RefCountedThreadSafe<WebMediaPlayerMSCompositor> {
  public:
   // This |url| represents the media stream we are rendering. |url| is used to
   // find out what web stream this WebMediaPlayerMSCompositor is playing, and
   // together with flag "--disable-rtc-smoothness-algorithm" determine whether
   // we enable algorithm or not.
   WebMediaPlayerMSCompositor(
       const scoped_refptr<base::SingleThreadTaskRunner>& compositor_task_runner,
       const blink::WebMediaStream& web_stream,
-      const base::WeakPtr<WebMediaPlayerMS>& player,
-      scoped_refptr<media::MediaLog> media_log_);
+      const base::WeakPtr<WebMediaPlayerMS>& player);
 
   void EnqueueFrame(scoped_refptr<media::VideoFrame> frame);
 
   // Statistical data
   gfx::Size GetCurrentSize();
   base::TimeDelta GetCurrentTime();
   size_t total_frame_count();
   size_t dropped_frame_count();
 
   // VideoFrameProvider implementation.
@@ skipping 44 matching lines @@
 
   // Used for DCHECKs to ensure method calls executed in the correct thread.
   base::ThreadChecker thread_checker_;
   base::ThreadChecker io_thread_checker_;
 
   scoped_refptr<base::SingleThreadTaskRunner> compositor_task_runner_;
   base::MessageLoop* main_message_loop_;
 
   base::WeakPtr<WebMediaPlayerMS> player_;
 
-  scoped_refptr<media::MediaLog> media_log_;
+  // TODO(qiangchen, emircan): It might be nice to use a real MediaLog here from
+  // the WebMediaPlayerMS instance, but it owns the MediaLog and this class has
+  // non-deterministic destruction paths (either compositor or IO).
+  media::MediaLog media_log_;
 
   size_t serial_;
 
   // A pointer back to the compositor to inform it about state changes. This
   // is not |nullptr| while the compositor is actively using this
   // VideoFrameProvider. This will be set to |nullptr| when the compositor stops
   // serving this VideoFrameProvider.
   cc::VideoFrameProvider::Client* video_frame_provider_client_;
 
   // |current_frame_| is updated only on compositor thread. The object it
@@ skipping 27 matching lines @@
 
   // |current_frame_lock_| protects |current_frame_used_by_compositor_|,
   // |current_frame_|, and |rendering_frame_buffer_|.
   base::Lock current_frame_lock_;
 
   DISALLOW_COPY_AND_ASSIGN(WebMediaPlayerMSCompositor);
 };
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_WEBMEDIAPLAYER_MS_COMPOSITOR_H_