Avoids crash in PCMWaveInAudioInputStream::WaveCallback

media/audio/win/wavein_input_win.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.
 
 #ifndef MEDIA_AUDIO_WIN_WAVEIN_INPUT_WIN_H_
 #define MEDIA_AUDIO_WIN_WAVEIN_INPUT_WIN_H_
 
 #include <string>
 
 #include <windows.h>
 #include <mmsystem.h>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
+#include "base/synchronization/lock.h"
 #include "base/win/scoped_handle.h"
 #include "media/audio/audio_io.h"
 #include "media/audio/audio_parameters.h"
 
 namespace media {
 
 class AudioManagerWin;
 
 class PCMWaveInAudioInputStream : public AudioInputStream {
  public:
@@ skipping 84 matching lines @@
 
   // Handle to the instance of the wave device.
   HWAVEIN wavein_;
 
   // Pointer to the first allocated audio buffer. This object owns it.
   WAVEHDR* buffer_;
 
   // An event that is signaled when the callback thread is ready to stop.
   base::win::ScopedHandle stopped_event_;
 
+  // Lock used to avoid conflicts when Stop() is called during a callback.
+  base::Lock lock_;
+
   DISALLOW_COPY_AND_ASSIGN(PCMWaveInAudioInputStream);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_WIN_WAVEIN_INPUT_WIN_H_