Revert of Pass task runners to AudioManager constructor.

media/audio/android/audio_manager_android.cc

Index: media/audio/android/audio_manager_android.cc
diff --git a/media/audio/android/audio_manager_android.cc b/media/audio/android/audio_manager_android.cc
index 35534b3cf022de233ed9c50452a6003e4870fbd8..96a7c78c29c055d099f5ee985a8a591bfe44c3a8 100644
--- a/media/audio/android/audio_manager_android.cc
+++ b/media/audio/android/audio_manager_android.cc
@@ -45,22 +45,12 @@
 
 }  // namespace
 
-ScopedAudioManagerPtr CreateAudioManager(
-    scoped_refptr<base::SingleThreadTaskRunner> task_runner,
-    scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
-    AudioLogFactory* audio_log_factory) {
-  return ScopedAudioManagerPtr(new AudioManagerAndroid(
-      std::move(task_runner), std::move(worker_task_runner),
-      audio_log_factory));
-}
-
-AudioManagerAndroid::AudioManagerAndroid(
-    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),
+AudioManager* CreateAudioManager(AudioLogFactory* audio_log_factory) {
+  return new AudioManagerAndroid(audio_log_factory);
+}
+
+AudioManagerAndroid::AudioManagerAndroid(AudioLogFactory* audio_log_factory)
+    : AudioManagerBase(audio_log_factory),
       communication_mode_is_on_(false),
       output_volume_override_set_(false),
       output_volume_override_(0) {
@@ -78,13 +68,11 @@
 }
 
 AudioManagerAndroid::~AudioManagerAndroid() {
-  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
+  // It's safe to post a task here since Shutdown() will wait for all tasks to
+  // complete before returning.
+  GetTaskRunner()->PostTask(FROM_HERE, base::Bind(
+      &AudioManagerAndroid::ShutdownOnAudioThread, base::Unretained(this)));
   Shutdown();
-
-  DVLOG(2) << "Destroying Java part of the audio manager";
-  Java_AudioManagerAndroid_close(base::android::AttachCurrentThread(),
-                                 j_audio_manager_.obj());
-  j_audio_manager_.Reset();
 }
 
 bool AudioManagerAndroid::HasAudioOutputDevices() {
@@ -349,6 +337,15 @@
       j_audio_manager_.obj());
 }
 
+void AudioManagerAndroid::ShutdownOnAudioThread() {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
+  DVLOG(2) << "Destroying Java part of the audio manager";
+  Java_AudioManagerAndroid_close(
+      base::android::AttachCurrentThread(),
+      j_audio_manager_.obj());
+  j_audio_manager_.Reset();
+}
+
 void AudioManagerAndroid::SetCommunicationAudioModeOn(bool on) {
   Java_AudioManagerAndroid_setCommunicationAudioModeOn(
       base::android::AttachCurrentThread(),