Use a shared thread for media operations.

webkit/media/webmediaplayer_impl.h

 // Copyright (c) 2012 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.
 
 // Delegate calls from WebCore::MediaPlayerPrivate to Chrome's video player.
 // It contains Pipeline which is the actual media player pipeline, it glues
 // the media player pipeline, data source, audio renderer and renderer.
 // Pipeline would creates multiple threads and access some public methods
 // of this class, so we need to be extra careful about concurrent access of
 // methods and members.
@@ skipping 262 matching lines @@
   WebKit::WebMediaPlayer::ReadyState ready_state_;
 
   // Keep a list of buffered time ranges.
   WebKit::WebTimeRanges buffered_;
 
   // Message loops for posting tasks on Chrome's main thread. Also used
   // for DCHECKs so methods calls won't execute in the wrong thread.
   const scoped_refptr<base::MessageLoopProxy> main_loop_;
 
   scoped_ptr<media::Pipeline> pipeline_;
-  base::Thread media_thread_;
+  scoped_refptr<base::MessageLoopProxy> media_loop_;
 
   // The currently selected key system. Empty string means that no key system
   // has been selected.
   WebKit::WebString current_key_system_;
 
   // Playback state.
   //
   // TODO(scherkus): we have these because Pipeline favours the simplicity of a
   // single "playback rate" over worrying about paused/stopped etc...  It forces
   // all clients to manage the pause+playback rate externally, but is that
@@ skipping 74 matching lines @@
   // A pointer back to the compositor to inform it about state changes. This is
   // not NULL while the compositor is actively using this webmediaplayer.
   cc::VideoFrameProvider::Client* video_frame_provider_client_;
 
   DISALLOW_COPY_AND_ASSIGN(WebMediaPlayerImpl);
 };
 
 }  // namespace webkit_media
 
 #endif  // WEBKIT_MEDIA_WEBMEDIAPLAYER_IMPL_H_