Clean up PlatformThread.

webrtc/modules/video_render/mac/video_render_nsopengl.h

Index: webrtc/modules/video_render/mac/video_render_nsopengl.h
diff --git a/webrtc/modules/video_render/mac/video_render_nsopengl.h b/webrtc/modules/video_render/mac/video_render_nsopengl.h
index 5993c088a7e8e8c944105621154537665176105b..a888b68a974ad094ee493eb31a99e47cf96f2a5f 100644
--- a/webrtc/modules/video_render/mac/video_render_nsopengl.h
+++ b/webrtc/modules/video_render/mac/video_render_nsopengl.h
@@ -30,9 +30,12 @@
 
 class Trace;
 
+namespace rtc {
+class PlatformThread;
+}  // namespace rtc
+
 namespace webrtc {
 class EventTimerWrapper;
-class PlatformThread;
 class VideoRenderNSOpenGL;
 class CriticalSectionWrapper;
 
@@ -166,7 +169,8 @@ private: // variables
     bool _fullScreen;
     int _id;
     CriticalSectionWrapper& _nsglContextCritSec;
-    rtc::scoped_ptr<PlatformThread> _screenUpdateThread;
+    // TODO(pbos): Remove scoped_ptr and use PlatformThread directly.
+    rtc::scoped_ptr<rtc::PlatformThread> _screenUpdateThread;
     EventTimerWrapper* _screenUpdateEvent;
     NSOpenGLContext* _nsglContext;
     NSOpenGLContext* _nsglFullScreenContext;