Modifies AudioInputCallback::OnData and use media::AudioBus instead of plain byte vector (Relanding)

media/audio/pulse/pulse_output.h

Index: media/audio/pulse/pulse_output.h
diff --git a/media/audio/pulse/pulse_output.h b/media/audio/pulse/pulse_output.h
index 437e28cb0ec0b77995bf3f72430b3626e0edfba9..e1c00455563974031bf75c5de0cae37f4ae3fad1 100644
--- a/media/audio/pulse/pulse_output.h
+++ b/media/audio/pulse/pulse_output.h
@@ -23,6 +23,7 @@
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
+#include "base/threading/thread_checker.h"
 #include "media/audio/audio_io.h"
 #include "media/audio/audio_parameters.h"
 
@@ -90,6 +91,8 @@ class PulseAudioOutputStream : public AudioOutputStream {
   // Container for retrieving data from AudioSourceCallback::OnMoreData().
   scoped_ptr<AudioBus> audio_bus_;
 
+  base::ThreadChecker thread_checker_;
+
   DISALLOW_COPY_AND_ASSIGN(PulseAudioOutputStream);
 };