Ensures that audio tasks cannot run after AudioManager is deleted.

media/audio/sounds/sounds_manager_unittest.cc

Index: media/audio/sounds/sounds_manager_unittest.cc
diff --git a/media/audio/sounds/sounds_manager_unittest.cc b/media/audio/sounds/sounds_manager_unittest.cc
index ac0234f44218dcccbb3567944c79da9bf1ff93f8..2118d4adda7ef18307b9c6c0c1ef0c5de3733fb3 100644
--- a/media/audio/sounds/sounds_manager_unittest.cc
+++ b/media/audio/sounds/sounds_manager_unittest.cc
@@ -34,6 +34,7 @@ class SoundsManagerTest : public testing::Test {
 
   void TearDown() override {
     SoundsManager::Shutdown();
+    audio_manager_->Shutdown();
     base::RunLoop().RunUntilIdle();
   }
 
@@ -48,7 +49,7 @@ class SoundsManagerTest : public testing::Test {
 
  private:
   base::TestMessageLoop message_loop_;
-  ScopedAudioManagerPtr audio_manager_;
+  std::unique_ptr<AudioManager> audio_manager_;
 };
 
 TEST_F(SoundsManagerTest, Play) {