alsa_output: Drain and pause pcm when stopping.

media/audio/linux/alsa_output.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.
 //
 // THREAD SAFETY
 //
 // AlsaPcmOutputStream object is *not* thread-safe and should only be used
 // from the audio thread.  We DCHECK on this assumption whenever we can.
 //
 // SEMANTICS OF Close()
@@ skipping 317 matching lines @@
       ScheduleNextWrite(false);
   }
 }
 
 void AlsaPcmOutputStream::Stop() {
   DCHECK(IsOnAudioThread());
 
   // Reset the callback, so that it is not called anymore.
   set_source_callback(NULL);
 
+  // Finish playing samples and pause the pcm.
+  wrapper_->PcmDrain(playback_handle_);
+
   TransitionTo(kIsStopped);
 }
 
 void AlsaPcmOutputStream::SetVolume(double volume) {
   DCHECK(IsOnAudioThread());
 
   volume_ = static_cast<float>(volume);
 }
 
 void AlsaPcmOutputStream::GetVolume(double* volume) {
@@ skipping 455 matching lines @@
 }
 
 // Changes the AudioSourceCallback to proxy calls to.  Pass in NULL to
 // release ownership of the currently registered callback.
 void AlsaPcmOutputStream::set_source_callback(AudioSourceCallback* callback) {
   DCHECK(IsOnAudioThread());
   source_callback_ = callback;
 }
 
 }  // namespace media