Merge 238501 "Attempt to fix audio wedges by restarting all stre..."

media/audio/audio_manager_base.cc

Index: media/audio/audio_manager_base.cc
===================================================================
--- media/audio/audio_manager_base.cc	(revision 240452)
+++ media/audio/audio_manager_base.cc	(working copy)
@@ -434,4 +434,32 @@
   return 0;
 }
 
+void AudioManagerBase::FixWedgedAudio() {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+#if defined(OS_MACOSX)
+  // Through trial and error, we've found that one way to restore audio after a
+  // hang is to close all outstanding audio streams.  Once all streams have been
+  // closed, new streams appear to work correctly.
+  //
+  // In Chrome terms, this means we need to ask all AudioOutputDispatchers to
+  // close all Open()'d streams.  Once all streams across all dispatchers have
+  // been closed, we ask for all previously Start()'d streams to be recreated
+  // using the same AudioSourceCallback they had before.
+  //
+  // Since this operation takes place on the audio thread we can be sure that no
+  // other state-changing stream operations will take place while the fix is in
+  // progress.
+  //
+  // See http://crbug.com/160920 for additional details.
+  for (AudioOutputDispatchers::iterator it = output_dispatchers_.begin();
+       it != output_dispatchers_.end(); ++it) {
+    (*it)->dispatcher->CloseStreamsForWedgeFix();
+  }
+  for (AudioOutputDispatchers::iterator it = output_dispatchers_.begin();
+       it != output_dispatchers_.end(); ++it) {
+    (*it)->dispatcher->RestartStreamsForWedgeFix();
+  }
+#endif
+}
+
 }  // namespace media