Cleanup namespace usage from animation to exported in platform/

Source/platform/audio/ReverbConvolver.h

Index: Source/platform/audio/ReverbConvolver.h
diff --git a/Source/platform/audio/ReverbConvolver.h b/Source/platform/audio/ReverbConvolver.h
index 32f0caef615af644e570c9aaeca2060707c59eb2..d257cd7844abef7ede00180e774fdba10102972b 100644
--- a/Source/platform/audio/ReverbConvolver.h
+++ b/Source/platform/audio/ReverbConvolver.h
@@ -40,12 +40,9 @@
 #include "wtf/Vector.h"
 
 namespace blink {
-class WebThread;
-}
-
-namespace blink {
 
 class AudioChannel;
+class WebThread;
 
 class PLATFORM_EXPORT ReverbConvolver {
     WTF_MAKE_NONCOPYABLE(ReverbConvolver);
@@ -83,7 +80,7 @@ private:
     size_t m_maxRealtimeFFTSize;
 
     // Background thread and synchronization
-    OwnPtr<blink::WebThread> m_backgroundThread;
+    OwnPtr<WebThread> m_backgroundThread;
 };
 
 } // namespace blink