Clean up PlatformThread.

webrtc/modules/audio_device/mac/audio_device_mac.h

Index: webrtc/modules/audio_device/mac/audio_device_mac.h
diff --git a/webrtc/modules/audio_device/mac/audio_device_mac.h b/webrtc/modules/audio_device/mac/audio_device_mac.h
index d908fc5752c170f37c7f523a082eb5017e9c2ba8..bb900e07aa62fd16e27ad97b6cc389bb3bc43a2d 100644
--- a/webrtc/modules/audio_device/mac/audio_device_mac.h
+++ b/webrtc/modules/audio_device/mac/audio_device_mac.h
@@ -23,10 +23,13 @@
 
 struct PaUtilRingBuffer;
 
+namespace rtc {
+class PlatformThread;
+}  // namespace rtc
+
 namespace webrtc
 {
 class EventWrapper;
-class PlatformThread;
 
 const uint32_t N_REC_SAMPLES_PER_SEC = 48000;
 const uint32_t N_PLAY_SAMPLES_PER_SEC = 48000;
@@ -282,11 +285,13 @@ private:
     EventWrapper& _stopEventRec;
     EventWrapper& _stopEvent;
 
+    // TODO(pbos): Replace with direct members, just start/stop, no need to
+    // recreate the thread.
     // Only valid/running between calls to StartRecording and StopRecording.
-    rtc::scoped_ptr<PlatformThread> capture_worker_thread_;
+    rtc::scoped_ptr<rtc::PlatformThread> capture_worker_thread_;
 
     // Only valid/running between calls to StartPlayout and StopPlayout.
-    rtc::scoped_ptr<PlatformThread> render_worker_thread_;
+    rtc::scoped_ptr<rtc::PlatformThread> render_worker_thread_;
 
     int32_t _id;