Fix implicit channel layout configurations at non-1.0 playback rates.

media/renderers/audio_renderer_impl.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.
 
 // Audio rendering unit utilizing an AudioRendererSink to output data.
 //
 // This class lives inside three threads during it's lifetime, namely:
 // 1. Render thread
 //    Where the object is created.
 // 2. Media thread (provided via constructor)
@@ skipping 178 matching lines @@
 
   // Called when the |decoder_|.Reset() has completed.
   void ResetDecoderDone();
 
   // Called by the AudioBufferStream when a config change occurs.
   void OnConfigChange();
 
   // Updates |buffering_state_| and fires |buffering_state_cb_|.
   void SetBufferingState_Locked(BufferingState buffering_state);
 
+  // Configure's the channel mask for |algorithm_|. Must be called if the layout
+  // changes. Expect the layout in |last_decoded_channel_layout_|.
+  void ConfigureChannelMask();
+
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
 
   std::unique_ptr<AudioBufferConverter> buffer_converter_;
 
   // Whether or not we expect to handle config changes.
   bool expecting_config_changes_;
 
   // The sink (destination) for rendered audio. |sink_| must only be accessed
   // on |task_runner_|. |sink_| must never be called under |lock_| or else we
   // may deadlock between |task_runner_| and the audio callback thread.
@@ skipping 18 matching lines @@
   std::unique_ptr<base::TickClock> tick_clock_;
 
   // Memory usage of |algorithm_| recorded during the last
   // HandleDecodedBuffer_Locked() call.
   int64_t last_audio_memory_usage_;
 
   // Sample rate of the last decoded audio buffer. Allows for detection of
   // sample rate changes due to implicit AAC configuration change.
   int last_decoded_sample_rate_;
 
-  // Indicates which channels are muted and can be ignored by the algorithm.
-  std::vector<bool> channel_mask_;
+  // Similar to |last_decoded_sample_rate_|, used to configure the channel mask
+  // given to the |algorithm_| for efficient playback rate changes.
+  ChannelLayout last_decoded_channel_layout_;
 
   // After Initialize() has completed, all variables below must be accessed
   // under |lock_|. ------------------------------------------------------------
   base::Lock lock_;
 
   // Algorithm for scaling audio.
   double playback_rate_;
   std::unique_ptr<AudioRendererAlgorithm> algorithm_;
 
   // Simple state tracking variable.
@@ skipping 44 matching lines @@
 
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<AudioRendererImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioRendererImpl);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_RENDERERS_AUDIO_RENDERER_IMPL_H_