Ensures that audio tasks cannot run after AudioManager is deleted.

media/audio/cras/audio_manager_cras.h

 // Copyright 2013 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_CRAS_AUDIO_MANAGER_CRAS_H_
 #define MEDIA_AUDIO_CRAS_AUDIO_MANAGER_CRAS_H_
 
 #include <cras_types.h>
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "media/audio/audio_manager_base.h"
 
 namespace media {
 
 class MEDIA_EXPORT AudioManagerCras : public AudioManagerBase {
  public:
   AudioManagerCras(
       scoped_refptr<base::SingleThreadTaskRunner> task_runner,
       scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
       AudioLogFactory* audio_log_factory);
+  ~AudioManagerCras() override;
 
   // AudioManager implementation.
   bool HasAudioOutputDevices() override;
   bool HasAudioInputDevices() override;
   void ShowAudioInputSettings() override;
   void GetAudioInputDeviceNames(AudioDeviceNames* device_names) override;
   void GetAudioOutputDeviceNames(AudioDeviceNames* device_names) override;
   AudioParameters GetInputStreamParameters(
       const std::string& device_id) override;
   const char* GetName() override;
@@ skipping 15 matching lines @@
       const std::string& device_id,
       const LogCallback& log_callback) override;
 
   static snd_pcm_format_t BitsToFormat(int bits_per_sample);
 
   // Checks if |device_id| corresponds to the default device.
   // Set |is_input| to true for capture devices, false for output.
   bool IsDefault(const std::string& device_id, bool is_input);
 
  protected:
-  ~AudioManagerCras() override;
-
   AudioParameters GetPreferredOutputStreamParameters(
       const std::string& output_device_id,
       const AudioParameters& input_params) override;
 
  private:
   // Called by MakeLinearOutputStream and MakeLowLatencyOutputStream.
   AudioOutputStream* MakeOutputStream(const AudioParameters& params,
                                       const std::string& device_id);
 
   // Called by MakeLinearInputStream and MakeLowLatencyInputStream.
   AudioInputStream* MakeInputStream(const AudioParameters& params,
                                     const std::string& device_id);
 
   void GetAudioDeviceNamesImpl(bool is_input, AudioDeviceNames* device_names);
 
   void AddBeamformingDevices(AudioDeviceNames* device_names);
 
   // Stores the mic positions field from the device.
   std::vector<Point> mic_positions_;
 
   const char* beamforming_on_device_id_;
   const char* beamforming_off_device_id_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioManagerCras);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_CRAS_AUDIO_MANAGER_CRAS_H_