Ensures that audio tasks cannot run after AudioManager is deleted.

media/audio/sounds/audio_stream_handler_unittest.cc

Index: media/audio/sounds/audio_stream_handler_unittest.cc
diff --git a/media/audio/sounds/audio_stream_handler_unittest.cc b/media/audio/sounds/audio_stream_handler_unittest.cc
index dc192cd4f49506507892e00b45dec52c68b3f438..08b8af7792ef370273a0b499e6e06045ca10fa07 100644
--- a/media/audio/sounds/audio_stream_handler_unittest.cc
+++ b/media/audio/sounds/audio_stream_handler_unittest.cc
@@ -40,6 +40,7 @@ class AudioStreamHandlerTest : public testing::Test {
 
   void TearDown() override {
     audio_stream_handler_.reset();
+    audio_manager_->Shutdown();
     base::RunLoop().RunUntilIdle();
   }
 
@@ -58,7 +59,7 @@ class AudioStreamHandlerTest : public testing::Test {
 
  private:
   base::TestMessageLoop message_loop_;
-  ScopedAudioManagerPtr audio_manager_;
+  std::unique_ptr<AudioManager> audio_manager_;
   std::unique_ptr<AudioStreamHandler> audio_stream_handler_;
 };