Ensures that audio tasks cannot run after AudioManager is deleted.

media/audio/pulse/audio_manager_pulse.cc

Index: media/audio/pulse/audio_manager_pulse.cc
diff --git a/media/audio/pulse/audio_manager_pulse.cc b/media/audio/pulse/audio_manager_pulse.cc
index 779bf92e58d3d39c981f398cf911ed504bc2191f..28511e839864150ccd3b1482e57c49a99203b74f 100644
--- a/media/audio/pulse/audio_manager_pulse.cc
+++ b/media/audio/pulse/audio_manager_pulse.cc
@@ -48,13 +48,9 @@ static const base::FilePath::CharType kPulseLib[] =
     FILE_PATH_LITERAL("libpulse.so.0");
 #endif
 
-AudioManagerPulse::AudioManagerPulse(
-    scoped_refptr<base::SingleThreadTaskRunner> task_runner,
-    scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
-    AudioLogFactory* audio_log_factory)
-    : AudioManagerBase(std::move(task_runner),
-                       std::move(worker_task_runner),
-                       audio_log_factory),
+AudioManagerPulse::AudioManagerPulse(std::unique_ptr<AudioThread> audio_thread,
+                                     AudioLogFactory* audio_log_factory)
+    : AudioManagerBase(std::move(audio_thread), audio_log_factory),
       input_mainloop_(NULL),
       input_context_(NULL),
       devices_(NULL),
@@ -63,12 +59,7 @@ AudioManagerPulse::AudioManagerPulse(
   SetMaxOutputStreamsAllowed(kMaxOutputStreams);
 }
 
-AudioManagerPulse::~AudioManagerPulse() {
-  Shutdown();
-  // The Pulse objects are the last things to be destroyed since Shutdown()
-  // needs them.
-  DestroyPulse();
-}
+AudioManagerPulse::~AudioManagerPulse() = default;
 
 bool AudioManagerPulse::Init() {
   // TODO(alokp): Investigate if InitPulse can happen on the audio thread.
@@ -79,7 +70,13 @@ bool AudioManagerPulse::Init() {
   return InitPulse();
 }
 
-// Implementation of AudioManager.
+void AudioManagerPulse::ShutdownOnAudioThread() {
+  AudioManagerBase::ShutdownOnAudioThread();
+  // The Pulse objects are the last things to be destroyed since Shutdown()
+  // needs them.
+  DestroyPulse();
+}
+
 bool AudioManagerPulse::HasAudioOutputDevices() {
   AudioDeviceNames devices;
   GetAudioOutputDeviceNames(&devices);