Ensures that audio tasks cannot run after AudioManager is deleted.

media/audio/mac/audio_auhal_mac_unittest.cc

Index: media/audio/mac/audio_auhal_mac_unittest.cc
diff --git a/media/audio/mac/audio_auhal_mac_unittest.cc b/media/audio/mac/audio_auhal_mac_unittest.cc
index e6f3878675e5feacd4bcfbb1f971d2f3af49f5c7..28f9123678d2951cee5e7bb271d156ca0277baa4 100644
--- a/media/audio/mac/audio_auhal_mac_unittest.cc
+++ b/media/audio/mac/audio_auhal_mac_unittest.cc
@@ -12,6 +12,7 @@
 #include "media/audio/audio_manager.h"
 #include "media/audio/audio_unittest_util.h"
 #include "media/audio/mock_audio_source_callback.h"
+#include "media/audio/test_audio_thread.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -38,7 +39,7 @@ class AUHALStreamTest : public testing::Test {
   AUHALStreamTest()
       : message_loop_(base::MessageLoop::TYPE_UI),
         manager_(AudioManager::CreateForTesting(
-            base::ThreadTaskRunnerHandle::Get())) {
+            base::MakeUnique<TestAudioThread>())) {
     // Wait for the AudioManager to finish any initialization on the audio loop.
     base::RunLoop().RunUntilIdle();
   }
@@ -59,7 +60,7 @@ class AUHALStreamTest : public testing::Test {
 
  protected:
   base::TestMessageLoop message_loop_;
-  ScopedAudioManagerPtr manager_;
+  std::unique_ptr<AudioManager> manager_;
   MockAudioSourceCallback source_;
   std::string log_message_;