Ensures that audio tasks cannot run after AudioManager is deleted.

media/audio/audio_manager.h

Index: media/audio/audio_manager.h
diff --git a/media/audio/audio_manager.h b/media/audio/audio_manager.h
index cd91b399d6d4595ce60faf0131baa65f9cfd8bca..3f7f36200baf530c056a96f478a304c5ebee77f1 100644
--- a/media/audio/audio_manager.h
+++ b/media/audio/audio_manager.h
@@ -14,6 +14,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/sequenced_task_runner_helpers.h"
 #include "base/strings/string16.h"
+#include "base/threading/thread_checker.h"
 #include "build/build_config.h"
 #include "media/audio/audio_device_description.h"
 #include "media/audio/audio_logging.h"
@@ -30,13 +31,6 @@ class AudioInputStream;
 class AudioManager;
 class AudioOutputStream;
 
-class MEDIA_EXPORT AudioManagerDeleter {
- public:
-  void operator()(const AudioManager* instance) const;
-};
-using ScopedAudioManagerPtr =
-    std::unique_ptr<AudioManager, AudioManagerDeleter>;
-
 // Manages all audio resources.  Provides some convenience functions that avoid
 // the need to provide iterators over the existing streams.
 //
@@ -44,6 +38,8 @@ using ScopedAudioManagerPtr =
 // thread hang is detected, it is reported to UMA.
 class MEDIA_EXPORT AudioManager {
  public:
+  virtual ~AudioManager();
+
   // Construct the audio manager; only one instance is allowed.
   // The returned instance must be deleted on AudioManager::GetTaskRunnner().
   //
@@ -63,7 +59,7 @@ class MEDIA_EXPORT AudioManager {
   //
   // |file_task_runner| is used for audio debug recordings and is the task
   // runner to do file output operations on.
-  static ScopedAudioManagerPtr Create(
+  static std::unique_ptr<AudioManager> Create(
       scoped_refptr<base::SingleThreadTaskRunner> task_runner,
       scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
       scoped_refptr<base::SingleThreadTaskRunner> file_task_runner,
@@ -71,7 +67,7 @@ class MEDIA_EXPORT AudioManager {
 
   // A convenience wrapper of AudioManager::Create for testing.
   // The given |task_runner| is shared for both audio io and heavyweight tasks.
-  static ScopedAudioManagerPtr CreateForTesting(
+  static std::unique_ptr<AudioManager> CreateForTesting(
       scoped_refptr<base::SingleThreadTaskRunner> task_runner);
 
   // Starts monitoring AudioManager task runner for hangs.
@@ -95,6 +91,10 @@ class MEDIA_EXPORT AudioManager {
   // like src/chrome.
   static AudioManager* Get();
 
+  // Releases all audio resources.
+  // Must be called on the audio thread.
+  virtual void Shutdown() = 0;
+
   // Returns true if the OS reports existence of audio devices. This does not
   // guarantee that the existing devices support all formats and sample rates.
   virtual bool HasAudioOutputDevices() = 0;
@@ -265,7 +265,6 @@ class MEDIA_EXPORT AudioManager {
 
   AudioManager(scoped_refptr<base::SingleThreadTaskRunner> task_runner,
                scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner);
-  virtual ~AudioManager();
 
   // Initializes output debug recording. Can be called on any thread; will post
   // to the audio thread if not called on it.
@@ -273,11 +272,9 @@ class MEDIA_EXPORT AudioManager {
       scoped_refptr<base::SingleThreadTaskRunner> file_task_runner) = 0;
 
  private:
-  friend class base::DeleteHelper<AudioManager>;
-  friend class AudioManagerDeleter;
-
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner_;
+  base::ThreadChecker thread_checker_;
   DISALLOW_COPY_AND_ASSIGN(AudioManager);
 };