AudioHardwareUnifiedStream::Stop() must not clear |source_| before calling AudioDeviceStop().

media/audio/mac/audio_unified_mac.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/mac/audio_unified_mac.h"
 
 #include <CoreServices/CoreServices.h>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
@@ skipping 260 matching lines @@
   OSSTATUS_DCHECK(result == noErr, result);
 
   if (result == noErr)
     is_playing_ = true;
 }
 
 void AudioHardwareUnifiedStream::Stop() {
   if (!is_playing_)
     return;
 
-  source_ = NULL;
-
   if (device_ != kAudioObjectUnknown) {
     OSStatus result = AudioDeviceStop(device_, io_proc_id_);
     OSSTATUS_DCHECK(result == noErr, result);
   }
 
   is_playing_ = false;
+  source_ = NULL;
 }
 
 void AudioHardwareUnifiedStream::SetVolume(double volume) {
   volume_ = static_cast<float>(volume);
   // TODO(crogers): set volume property
 }
 
 void AudioHardwareUnifiedStream::GetVolume(double* volume) {
   *volume = volume_;
 }
@@ skipping 91 matching lines @@
   return audio_output->Render(
       device,
       now,
       input_data,
       input_time,
       output_data,
       output_time);
 }
 
 }  // namespace media