Use aligned buffer in the audio mixer.

media/audio/audio_output_mixer.h

Index: media/audio/audio_output_mixer.h
===================================================================
--- media/audio/audio_output_mixer.h	(revision 140416)
+++ media/audio/audio_output_mixer.h	(working copy)
@@ -21,6 +21,7 @@
 #include "media/audio/audio_manager.h"
 #include "media/audio/audio_output_dispatcher.h"
 #include "media/audio/audio_parameters.h"
+#include "media/base/decoder_buffer.h"
 
 namespace media {
 
@@ -77,7 +78,7 @@
 
   // Temporary buffer used when mixing. Allocated in the constructor
   // to avoid constant allocation/deallocation in the callback.
-  scoped_array<uint8> mixer_data_;
+  scoped_refptr<DecoderBuffer> mixer_data_;
 
   // Used to post delayed tasks to ourselves that we cancel inside Shutdown().
   base::WeakPtrFactory<AudioOutputMixer> weak_this_;