Switch audio hang monitor to default-off. Enable for non-beta,stable.

media/base/media_switches.cc

Index: media/base/media_switches.cc
diff --git a/media/base/media_switches.cc b/media/base/media_switches.cc
index 43904123893639c8543d56306975e8245e0a9665..c42bd9ff0ec8ccdeed666c6b76cfa1e9b1f6428c 100644
--- a/media/base/media_switches.cc
+++ b/media/base/media_switches.cc
@@ -84,6 +84,11 @@ const char kWaveOutBuffers[] = "waveout-buffers";
 const char kUseCras[] = "use-cras";
 #endif
 
+// Enables the audio thread hang monitor.  Allows us to find users in the field
+// who have stuck audio threads.  See crbug.com/422522 and crbug.com/478932.
+// TODO(dalecurtis): This should be removed once those issues are resolved.
+const char kEnableAudioHangMonitor[] = "enable-audio-hang-monitor";
+
 // Use fake device for Media Stream to replace actual camera and microphone.
 const char kUseFakeDeviceForMediaStream[] = "use-fake-device-for-media-stream";