Adding syncrhonization to PulseAudioOutputStream::SetVolume

media/audio/pulse/pulse_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.
 
 #include "media/audio/pulse/pulse_output.h"
 
 #include <pulse/pulseaudio.h>
 #include <stdint.h>
 
 #include "base/single_thread_task_runner.h"
@@ skipping 209 matching lines @@
   WaitForOperationCompletion(pa_mainloop_, operation);
 
   operation = pa_stream_cork(pa_stream_, 1, &pulse::StreamSuccessCallback,
                              pa_mainloop_);
   WaitForOperationCompletion(pa_mainloop_, operation);
 }
 
 void PulseAudioOutputStream::SetVolume(double volume) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
+  // Waiting for the main loop lock will ensure outstanding callbacks have
+  // completed and |volume_| is not accessed from them.
+  AutoPulseLock auto_lock(pa_mainloop_);
   volume_ = static_cast<float>(volume);
 }
 
 void PulseAudioOutputStream::GetVolume(double* volume) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   *volume = volume_;
 }
 
 }  // namespace media