Fix regression with audio mirroring due to observers being added while iterating over the list of ob

media/audio/audio_output_controller.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_output_controller.h"
 
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
 #include "base/message_loop.h"
 #include "base/synchronization/waitable_event.h"
@@ skipping 123 matching lines @@
     state_ = kError;
     DoStopCloseAndClearStream(NULL);
 
     // TODO(hclam): Define error types.
     handler_->OnError(this, 0);
     return;
   }
 
   // Everything started okay, so register for state change callbacks if we have
   // not already done so.
-  audio_manager_->AddOutputDeviceChangeListener(this);
+  if (state_ != kRecreating)

[miu, 2013/01/04 21:57:56]

This will leave us in a state where AOC is not registered as a device change
listener.  That's because DoStopCloseAndClearStream() calls
RemoveOutputDeviceChangeListener() whether we're re-creating or not.  So, we
unconditionally want to call AddOutputDeviceChangeListener here.

It looks like this change is just covering up another bug somewhere?

[justinlin, 2013/01/04 22:31:02]

Right. Hmm, I saw a DCHECK failure due to this (observer registering twice), but
that may be when I was debugging. Yea, I see the problem now, it's getting into
an infinite OnDeviceChanged loop for some reason. Will update patch soon with a
better solution.

+    audio_manager_->AddOutputDeviceChangeListener(this);
 
   // We have successfully opened the stream. Set the initial volume.
   stream_->SetVolume(volume_);
 
   // Finally set the state to kCreated.
   State original_state = state_;
   state_ = kCreated;
 
   // And then report we have been created if we haven't done so already.
   if (original_state != kRecreating)
@@ skipping 232 matching lines @@
     case kPausedWhenStarting:
     case kPaused:
       // From the outside these three states are equivalent.
       return;
     default:
       NOTREACHED() << "Invalid original state.";
   }
 }
 
 }  // namespace media