Revert 142862 - Change the way we are stopping audio stream on Mac once again.

media/audio/mac/audio_output_mac.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_MAC_AUDIO_OUTPUT_MAC_H_
 #define MEDIA_AUDIO_MAC_AUDIO_OUTPUT_MAC_H_
 
 #include <AudioToolbox/AudioFormat.h>
 #include <AudioToolbox/AudioQueue.h>
 #include <AudioUnit/AudioUnit.h>
@@ skipping 33 matching lines @@
   // The audio is double buffered.
   static const uint32 kNumBuffers = 2;
   static const int kEmptyChannel = -1;
 
   // Reorder PCM from source layout to device layout found in Core Audio.
   template<class Format>
   void SwizzleLayout(Format* b, uint32 filled);
   // Check and move channels if surround sound layout needs adjusted.
   bool CheckForAdjustedLayout(Channels input_channel, Channels output_channel);
 
-  // Callback we are installing to find out when the stream is stopped.
-  static void IsRunningCallback(void* p_this,
-                                AudioQueueRef queue,
-                                AudioQueuePropertyID inID);
-
   // The OS calls back here when an audio buffer has been processed.
   static void RenderCallback(void* p_this, AudioQueueRef queue,
                              AudioQueueBufferRef buffer);
   // Called when an error occurs.
   void HandleError(OSStatus err);
 
   // Atomic operations for setting/getting the source callback.
   void SetSource(AudioSourceCallback* source);
   AudioSourceCallback* GetSource();
 
@@ skipping 27 matching lines @@
   // An array for remapping source to device channel layouts during a swizzle.
   int channel_remap_[CHANNELS_MAX];
   // Number of channels in device layout.
   int num_core_channels_;
   // A flag to determine if swizzle is needed from source to device layouts.
   bool should_swizzle_;
   // A flag to determine if downmix is needed from source to device layouts.
   bool should_down_mix_;
 
   // Event used for synchronization when stopping the stream.
-  // Callback sets it after stream is fully stopped.
+  // Callback sets it after stream is stopped.
   base::WaitableEvent stopped_event_;
-  // Flag set by rendering callback when it asks OS to stop the stream.
-  // All subsequent renderer callbacks calls just exit immediately, they
-  // are called to release the buffer (and we do it when closing the stream,
-  // not in the callback).
-  bool stop_requested_;
+  // When stopping we keep track of number of buffers in flight and
+  // signal "stop completed" from the last buffer's callback.
+  int num_buffers_left_;
 
   DISALLOW_COPY_AND_ASSIGN(PCMQueueOutAudioOutputStream);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_MAC_AUDIO_OUTPUT_MAC_H_