Ensures that audio tasks cannot run after AudioManager is deleted.

media/audio/mac/audio_manager_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.
 
 #ifndef MEDIA_AUDIO_MAC_AUDIO_MANAGER_MAC_H_
 #define MEDIA_AUDIO_MAC_AUDIO_MANAGER_MAC_H_
 
 #include <AudioUnit/AudioUnit.h>
 #include <CoreAudio/AudioHardware.h>
 #include <stddef.h>
@@ skipping 15 matching lines @@
 
 // Mac OS X implementation of the AudioManager singleton. This class is internal
 // to the audio output and only internal users can call methods not exposed by
 // the AudioManager class.
 class MEDIA_EXPORT AudioManagerMac : public AudioManagerBase {
  public:
   AudioManagerMac(
       scoped_refptr<base::SingleThreadTaskRunner> task_runner,
       scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
       AudioLogFactory* audio_log_factory);
+  ~AudioManagerMac() override;
 
   // Implementation of AudioManager.
+  void Shutdown() override;
   bool HasAudioOutputDevices() override;
   bool HasAudioInputDevices() override;
   void GetAudioInputDeviceNames(AudioDeviceNames* device_names) override;
   void GetAudioOutputDeviceNames(AudioDeviceNames* device_names) override;
   AudioParameters GetInputStreamParameters(
       const std::string& device_id) override;
   std::string GetAssociatedOutputDeviceID(
       const std::string& input_device_id) override;
   const char* GetName() override;
 
@@ skipping 70 matching lines @@
                              size_t* io_buffer_frame_size);
 
   // Number of constructed output and input streams.
   size_t output_streams() const { return output_streams_.size(); }
   size_t low_latency_input_streams() const {
     return low_latency_input_streams_.size();
   }
   size_t basic_input_streams() const { return basic_input_streams_.size(); }
 
  protected:
-  ~AudioManagerMac() override;
   AudioParameters GetPreferredOutputStreamParameters(
       const std::string& output_device_id,
       const AudioParameters& input_params) override;
 
  private:
   void InitializeOnAudioThread();
 
   int ChooseBufferSize(bool is_input, int sample_rate);
 
   // Notify streams of a device change if the default output device or its
@@ skipping 47 matching lines @@
   // Set to true in the destructor. Ensures that methods that touches native
   // Core Audio APIs are not executed during shutdown.
   bool in_shutdown_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioManagerMac);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_MAC_AUDIO_MANAGER_MAC_H_