Ensures that audio tasks cannot run after AudioManager is deleted.

chromecast/media/audio/cast_audio_mixer_unittest.cc

Index: chromecast/media/audio/cast_audio_mixer_unittest.cc
diff --git a/chromecast/media/audio/cast_audio_mixer_unittest.cc b/chromecast/media/audio/cast_audio_mixer_unittest.cc
index 6d716f25bec5df3ecf2306e6cce3ac438f8c8d59..c0f47cb23b630b97295843fb4e05facd698452db 100644
--- a/chromecast/media/audio/cast_audio_mixer_unittest.cc
+++ b/chromecast/media/audio/cast_audio_mixer_unittest.cc
@@ -11,11 +11,13 @@
 #include <vector>
 
 #include "base/bind.h"
+#include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/time/time.h"
 #include "chromecast/media/audio/cast_audio_manager.h"
 #include "chromecast/media/audio/cast_audio_output_stream.h"
+#include "media/audio/test_audio_thread.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -85,10 +87,8 @@ class MockCastAudioOutputStream : public CastAudioOutputStream {
 
 class MockCastAudioManager : public CastAudioManager {
  public:
-  MockCastAudioManager(scoped_refptr<base::SingleThreadTaskRunner> task_runner,
-                       CastAudioMixer* audio_mixer)
-      : CastAudioManager(task_runner,
-                         task_runner,
+  MockCastAudioManager(CastAudioMixer* audio_mixer)
+      : CastAudioManager(base::MakeUnique<::media::TestAudioThread>(),
                          nullptr,
                          nullptr,
                          audio_mixer) {
@@ -141,13 +141,12 @@ class CastAudioMixerTest : public ::testing::Test {
     mock_mixer_ = new StrictMock<MockCastAudioMixer>(
         base::Bind(&CastAudioMixerTest::MakeMixerOutputStreamProxy,
                    base::Unretained(this)));
-    mock_manager_.reset(new StrictMock<MockCastAudioManager>(
-        message_loop_.task_runner(), mock_mixer_));
+    mock_manager_.reset(new StrictMock<MockCastAudioManager>(mock_mixer_));
     mock_mixer_stream_.reset(new StrictMock<MockCastAudioOutputStream>(
         GetAudioParams(), mock_manager_.get()));
   }
 
-  void TearDown() override { mock_manager_.reset(); }
+  void TearDown() override { mock_manager_->Shutdown(); }
 
   MockCastAudioManager& mock_manager() { return *mock_manager_; }