Use the browser UI thread for audio on OSX.

content/test/webrtc_audio_device_test.cc

Index: content/test/webrtc_audio_device_test.cc
diff --git a/content/test/webrtc_audio_device_test.cc b/content/test/webrtc_audio_device_test.cc
index 63fbf1393db625bff80de561c05f5fcdf7e2d07f..caa259ce0c7c8387875a77fc0c246bbeb34b5e2c 100644
--- a/content/test/webrtc_audio_device_test.cc
+++ b/content/test/webrtc_audio_device_test.cc
@@ -140,6 +140,8 @@ void WebRTCAudioDeviceTest::SetUp() {
 
   // Construct the resource context on the UI thread.
   resource_context_.reset(new MockRTCResourceContext);
+  audio_manager_.reset(media::AudioManager::Create());
+  mirroring_manager_.reset(new AudioMirroringManager());
 
   static const char kThreadName[] = "RenderThread";
   ChildProcess::current()->io_message_loop()->PostTask(FROM_HERE,
@@ -181,6 +183,7 @@ void WebRTCAudioDeviceTest::TearDown() {
   media_stream_manager_.reset();
   mirroring_manager_.reset();
   audio_manager_.reset();
+
   RendererWebKitPlatformSupportImpl::SetSandboxEnabledForTesting(
       sandbox_was_enabled_);
 }
@@ -211,10 +214,6 @@ void WebRTCAudioDeviceTest::InitializeIOThread(const char* thread_name) {
       static_cast<MockRTCResourceContext*>(resource_context_.get());
   resource_context->set_request_context(test_request_context_.get());
   media_internals_.reset(new MockMediaInternals());
-
-  // Create our own AudioManager, AudioMirroringManager and MediaStreamManager.
-  audio_manager_.reset(media::AudioManager::Create());
-  mirroring_manager_.reset(new AudioMirroringManager());
   media_stream_manager_.reset(new MediaStreamManager(audio_manager_.get()));
 
   has_input_devices_ = audio_manager_->HasAudioInputDevices();