Use the browser UI thread for audio on OSX.

media/base/media_switches.cc

 // 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.
 
 #include "media/base/media_switches.h"
 
 namespace switches {
 
 // Allow users to specify a custom buffer size for debugging purpose.
 const char kAudioBufferSize[] = "audio-buffer-size";
 
-#if defined(OS_LINUX) || defined(OS_FREEBSD) || defined(OS_SOLARIS)
-// The Alsa device to use when opening an audio stream.
-const char kAlsaOutputDevice[] = "alsa-output-device";
-// The Alsa device to use when opening an audio input stream.
-const char kAlsaInputDevice[] = "alsa-input-device";
-#endif
-
-#if defined(USE_CRAS)
-// Use CRAS, the ChromeOS audio server.
-const char kUseCras[] = "use-cras";
-#endif
-
-#if defined(OS_WIN)
-// Use exclusive mode audio streaming for Windows Vista and higher.
-// Leads to lower latencies for audio streams which uses the
-// AudioParameters::AUDIO_PCM_LOW_LATENCY audio path.
-// See http://msdn.microsoft.com/en-us/library/windows/desktop/dd370844(v=vs.85).aspx
-// for details.
-const char kEnableExclusiveAudio[] = "enable-exclusive-audio";
-
-// Use Windows WaveOut/In audio API even if Core Audio is supported.
-const char kForceWaveAudio[] = "force-wave-audio";
-#endif
-
-// Set number of threads to use for video decoding.
-const char kVideoThreads[] = "video-threads";
+// Enable EAC3 playback in MSE.
+const char kEnableEac3Playback[] = "enable-eac3-playback";
 
 // Enables Opus playback in media elements.
 const char kEnableOpusPlayback[] = "enable-opus-playback";
 
+// Enables VP8 Alpha playback in media elements.
+const char kEnableVp8AlphaPlayback[] = "enable-vp8-alpha-playback";
+
 // Enables VP9 playback in media elements.
 const char kEnableVp9Playback[] = "enable-vp9-playback";
 
-// Enables VP8 Alpha playback in media elements.
-const char kEnableVp8AlphaPlayback[] = "enable-vp8-alpha-playback";
-
-// Enable EAC3 playback in MSE.
-const char kEnableEac3Playback[] = "enable-eac3-playback";
-
-#if defined(OS_WIN)
-const char kWaveOutBuffers[] = "waveout-buffers";
-#endif
+// Set number of threads to use for video decoding.
+const char kVideoThreads[] = "video-threads";
 
 #if defined(GOOGLE_TV)
 // Use external video surface for video with more than or equal pixels to
 // specified value. For example, value of 0 will enable external video surface
 // for all videos, and value of 921600 (=1280*720) will enable external video
 // surface for 720p video and larger.
 const char kUseExternalVideoSurfaceThresholdInPixels[] =
     "use-external-video-surface-threshold-in-pixels";
 #endif
 
+#if defined(OS_LINUX) || defined(OS_FREEBSD) || defined(OS_SOLARIS)
+// The Alsa device to use when opening an audio input stream.
+const char kAlsaInputDevice[] = "alsa-input-device";
+// The Alsa device to use when opening an audio stream.
+const char kAlsaOutputDevice[] = "alsa-output-device";
+#endif
+
+#if defined(OS_MACOSX)
+// Unlike other platforms, OSX requires CoreAudio calls to happen on the main
+// thread of the process.  Provide a way to disable this until support is well
+// tested.  See http://crbug.com/158170.
+// TODO(dalecurtis): Remove this once we're sure nothing has exploded.
+const char kDisableMainThreadAudio[] = "disable-main-thread-audio";
+#endif
+
+#if defined(OS_WIN)
+// Use exclusive mode audio streaming for Windows Vista and higher.
+// Leads to lower latencies for audio streams which uses the
+// AudioParameters::AUDIO_PCM_LOW_LATENCY audio path.
+// See http://msdn.microsoft.com/en-us/library/windows/desktop/dd370844.aspx
+// for details.
+const char kEnableExclusiveAudio[] = "enable-exclusive-audio";
+
+// Use Windows WaveOut/In audio API even if Core Audio is supported.
+const char kForceWaveAudio[] = "force-wave-audio";
+
+// Number of buffers to use for WaveOut.
+const char kWaveOutBuffers[] = "waveout-buffers";
+#endif
+
+#if defined(USE_CRAS)
+// Use CRAS, the ChromeOS audio server.
+const char kUseCras[] = "use-cras";
+#endif
 
 }  // namespace switches