Avoid hitting the thread check when WebRtcAudioRenderer is going away.

content/renderer/media/webrtc_audio_renderer.cc

 // 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.
 
 #include "content/renderer/media/webrtc_audio_renderer.h"
 
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
@@ skipping 404 matching lines @@
 
   DCHECK_EQ(state_, PLAYING);
   DCHECK_GT(play_ref_count_, 0);
   if (!--play_ref_count_)
     state_ = PAUSED;
 }
 
 void WebRtcAudioRenderer::Stop() {
   DVLOG(1) << "WebRtcAudioRenderer::Stop()";
   DCHECK(thread_checker_.CalledOnValidThread());
+  // Make sure to stop the sink while _not_ holding the lock since the Render()
+  // callback may currently be executing and try to grab the lock while we're
+  // stopping the thread on which it runs.
+  // Stop the sink before calling RemoveAudioRenderer() to make sure that no
+  // more callbacks will be made while the renderer is being removed.
+  sink_->Stop();
+
   {
     base::AutoLock auto_lock(lock_);
     if (state_ == UNINITIALIZED)
       return;
 
     if (--start_ref_count_)
       return;
 
     DVLOG(1) << "Calling RemoveAudioRenderer and Stop().";
 
     source_->RemoveAudioRenderer(this);
     source_ = NULL;
     state_ = UNINITIALIZED;
   }
-
-  // Make sure to stop the sink while _not_ holding the lock since the Render()
-  // callback may currently be executing and try to grab the lock while we're
-  // stopping the thread on which it runs.
-  sink_->Stop();
 }
 
 void WebRtcAudioRenderer::SetVolume(float volume) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(volume >= 0.0f && volume <= 1.0f);
 
   playing_state_.set_volume(volume);
   OnPlayStateChanged(media_stream_, &playing_state_);
 }
 
@@ skipping 129 matching lines @@
       if (RemovePlayingState(source, state))
         EnterPauseState();
     } else if (AddPlayingState(source, state)) {
       EnterPlayState();
     }
     UpdateSourceVolume(source);
   }
 }
 
 }  // namespace content