Cleanup redundant namespace usage in Source/platform

Source/platform/Prerender.h

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 25 matching lines @@
 #include "platform/weborigin/KURL.h"
 #include "platform/weborigin/ReferrerPolicy.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefCounted.h"
 #include "wtf/RefPtr.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
-class WebPrerender;
-}
-
-namespace blink {
 
 class PrerenderClient;
+class WebPrerender;
 
 class PLATFORM_EXPORT Prerender : public RefCounted<Prerender> {
     WTF_MAKE_NONCOPYABLE(Prerender);
 public:
     class ExtraData : public RefCounted<ExtraData> {
     public:
         virtual ~ExtraData() { }
     };
 
     static PassRefPtr<Prerender> create(PrerenderClient*, const KURL&, unsigned relTypes, const String& referrer, ReferrerPolicy);
@@ skipping 27 matching lines @@
     const unsigned m_relTypes;
     const String m_referrer;
     const ReferrerPolicy m_referrerPolicy;
 
     RefPtr<ExtraData> m_extraData;
 };
 
 }
 
 #endif // Prerender_h