Make the CancellableSyncSocket non-blocking on Send, and blocking on Receive

content/browser/renderer_host/media/audio_sync_reader.h

Index: content/browser/renderer_host/media/audio_sync_reader.h
diff --git a/content/browser/renderer_host/media/audio_sync_reader.h b/content/browser/renderer_host/media/audio_sync_reader.h
index 60a287971f97497074ad9512b62be5f5ac16fea2..8aef113af14d7f2fbe7c957a3b66506e7d8816d3 100644
--- a/content/browser/renderer_host/media/audio_sync_reader.h
+++ b/content/browser/renderer_host/media/audio_sync_reader.h
@@ -52,12 +52,6 @@ class AudioSyncReader : public media::AudioOutputController::SyncReader {
   // PrepareForeignSocketHandle() is called and ran successfully.
   scoped_ptr<base::CancelableSyncSocket> foreign_socket_;
 
-  // Protect socket_ access by lock to prevent race condition when audio
-  // controller thread closes the reader and hardware audio thread is reading
-  // data. This way we know that socket would not be deleted while we are
-  // writing data to it.
-  base::Lock lock_;
-
   DISALLOW_COPY_AND_ASSIGN(AudioSyncReader);
 };