Attempt to fix audio wedges by restarting all streams.

media/audio/audio_manager_base.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/audio/audio_manager_base.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/message_loop/message_loop_proxy.h"
@@ skipping 400 matching lines @@
   const CommandLine* cmd_line = CommandLine::ForCurrentProcess();
   int buffer_size = 0;
   std::string buffer_size_str(cmd_line->GetSwitchValueASCII(
       switches::kAudioBufferSize));
   if (base::StringToInt(buffer_size_str, &buffer_size) && buffer_size > 0)
     return buffer_size;
 
   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