Resolves crash in device notifier for audio input on Mac OS X

media/audio/mac/audio_low_latency_input_mac.h

Index: media/audio/mac/audio_low_latency_input_mac.h
diff --git a/media/audio/mac/audio_low_latency_input_mac.h b/media/audio/mac/audio_low_latency_input_mac.h
index 59dd618dad4d9952eaf5837beeaeb613085f9373..4881646c99d56cc6dd1710d000f479de483929b6 100644
--- a/media/audio/mac/audio_low_latency_input_mac.h
+++ b/media/audio/mac/audio_low_latency_input_mac.h
@@ -39,11 +39,13 @@
 #include <AudioUnit/AudioUnit.h>
 #include <CoreAudio/CoreAudio.h>
 #include <map>
+#include <vector>
 
 #include "base/atomicops.h"
 #include "base/cancelable_callback.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
 #include "base/threading/thread_checker.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
@@ -122,6 +124,10 @@ class MEDIA_EXPORT AUAudioInputStream
                                  UInt32 num_addresses,
                                  const AudioObjectPropertyAddress addresses[]);
 
+  // Updates the |device_property_changes_map_| on the main browser thread,
+  // (CrBrowserMain) which is the same thread as this instance is created on.
+  void DevicePropertyChangedOnMainThread(const std::vector<UInt32>& properties);
+
   // Registers OnDevicePropertyChanged() to receive notifications when device
   // properties changes.
   void RegisterDeviceChangeListener();
@@ -283,6 +289,11 @@ class MEDIA_EXPORT AUAudioInputStream
   UInt32 largest_glitch_frames_;
   int glitches_detected_;
 
+  // Used to ensure DevicePropertyChangedOnMainThread() is not called when
+  // this object is destroyed.
+  // Note that, all member variables should appear before the WeakPtrFactory.
+  base::WeakPtrFactory<AUAudioInputStream> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(AUAudioInputStream);
 };