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

media/audio/mac/audio_low_latency_input_mac.h

 // 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.
 //
 // Implementation of AudioInputStream for Mac OS X using the special AUHAL
 // input Audio Unit present in OS 10.4 and later.
 // The AUHAL input Audio Unit is for low-latency audio I/O.
 //
 // Overview of operation:
 //
@@ skipping 21 matching lines @@
 //      latency;
 //   2) The delay between the actual recording instant and the time when the
 //      data packet is provided as a callback.
 //
 #ifndef MEDIA_AUDIO_MAC_AUDIO_LOW_LATENCY_INPUT_MAC_H_
 #define MEDIA_AUDIO_MAC_AUDIO_LOW_LATENCY_INPUT_MAC_H_
 
 #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"
 #include "media/audio/agc_audio_stream.h"
 #include "media/audio/audio_io.h"
 #include "media/audio/audio_parameters.h"
 #include "media/base/audio_block_fifo.h"
 
 namespace media {
 
@@ skipping 58 matching lines @@
   // framework. These methods are called when device properties are changed.
   static OSStatus OnDevicePropertyChanged(
       AudioObjectID object_id,
       UInt32 num_addresses,
       const AudioObjectPropertyAddress addresses[],
       void* context);
   OSStatus DevicePropertyChanged(AudioObjectID object_id,
                                  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();
   // Stop listening for changes in device properties.
   void DeRegisterDeviceChangeListener();
 
   // Gets the fixed capture hardware latency and store it during initialization.
   // Returns 0 if not available.
   double GetHardwareLatency();
 
@@ skipping 141 matching lines @@
   // callback audio thread.
   // These variables are only touched on the callback thread and then read
   // in the dtor (when no longer receiving callbacks).
   // NOTE: Float64 and UInt32 types are used for native API compatibility.
   Float64 last_sample_time_;
   UInt32 last_number_of_frames_;
   UInt32 total_lost_frames_;
   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);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_MAC_AUDIO_LOW_LATENCY_INPUT_MAC_H_