Use the browser UI thread for audio on OSX.

media/base/media_switches.h

Index: media/base/media_switches.h
diff --git a/media/base/media_switches.h b/media/base/media_switches.h
index 11eb0b3cfde17ea1e04187eb6928f66c67543fe8..3e547b29e9ec554204d50881f7a2b5cac4f57006 100644
--- a/media/base/media_switches.h
+++ b/media/base/media_switches.h
@@ -12,38 +12,39 @@
 
 namespace switches {
 
-#if defined(OS_LINUX) || defined(OS_FREEBSD) || defined(OS_SOLARIS)
-extern const char kAlsaOutputDevice[];
-extern const char kAlsaInputDevice[];
-#endif
-
 MEDIA_EXPORT extern const char kAudioBufferSize[];
 
-#if defined(USE_CRAS)
-MEDIA_EXPORT extern const char kUseCras[];
-#endif
-
-#if defined(OS_WIN)
-MEDIA_EXPORT extern const char kEnableExclusiveAudio[];
-MEDIA_EXPORT extern const char kForceWaveAudio[];
-#endif
-
-MEDIA_EXPORT extern const char kVideoThreads[];
+MEDIA_EXPORT extern const char kEnableEac3Playback[];
 
 MEDIA_EXPORT extern const char kEnableOpusPlayback[];
 
+MEDIA_EXPORT extern const char kEnableVp8AlphaPlayback[];
+
 MEDIA_EXPORT extern const char kEnableVp9Playback[];
 
-MEDIA_EXPORT extern const char kEnableVp8AlphaPlayback[];
+MEDIA_EXPORT extern const char kVideoThreads[];
 
-MEDIA_EXPORT extern const char kEnableEac3Playback[];
+#if defined(GOOGLE_TV)
+MEDIA_EXPORT extern const char kUseExternalVideoSurfaceThresholdInPixels[];
+#endif
+
+#if defined(OS_LINUX) || defined(OS_FREEBSD) || defined(OS_SOLARIS)
+MEDIA_EXPORT extern const char kAlsaInputDevice[];
+MEDIA_EXPORT extern const char kAlsaOutputDevice[];
+#endif
+
+#if defined(OS_MACOSX)
+MEDIA_EXPORT extern const char kDisableMainThreadAudio[];
+#endif
 
 #if defined(OS_WIN)
+MEDIA_EXPORT extern const char kEnableExclusiveAudio[];
+MEDIA_EXPORT extern const char kForceWaveAudio[];
 MEDIA_EXPORT extern const char kWaveOutBuffers[];
 #endif
 
-#if defined(GOOGLE_TV)
-MEDIA_EXPORT extern const char kUseExternalVideoSurfaceThresholdInPixels[];
+#if defined(USE_CRAS)
+MEDIA_EXPORT extern const char kUseCras[];
 #endif
 
 }  // namespace switches