Revert of Pass task runners to AudioManager constructor.

media/audio/mock_audio_manager.cc

Index: media/audio/mock_audio_manager.cc
diff --git a/media/audio/mock_audio_manager.cc b/media/audio/mock_audio_manager.cc
index e7726ca3f3ec9c1556643fadbe5cd1d3b62a4f20..7183405a19063f1e44800336e1867ba7d4a9c733 100644
--- a/media/audio/mock_audio_manager.cc
+++ b/media/audio/mock_audio_manager.cc
@@ -11,8 +11,8 @@
 namespace media {
 
 MockAudioManager::MockAudioManager(
-    scoped_refptr<base::SingleThreadTaskRunner> task_runner)
-    : AudioManager(task_runner, task_runner) {}
+    const scoped_refptr<base::SingleThreadTaskRunner>& task_runner)
+    : task_runner_(task_runner) {}
 
 MockAudioManager::~MockAudioManager() {
 }
@@ -63,6 +63,15 @@
   return NULL;
 }
 
+scoped_refptr<base::SingleThreadTaskRunner> MockAudioManager::GetTaskRunner() {
+  return task_runner_;
+}
+
+scoped_refptr<base::SingleThreadTaskRunner>
+MockAudioManager::GetWorkerTaskRunner() {
+  return task_runner_;
+}
+
 void MockAudioManager::AddOutputDeviceChangeListener(
     AudioDeviceListener* listener) {
 }