Cleanup namespace usage in platform/graphics/[filters/* to skia/*] and platform/graphics/[B-D]*

Source/platform/graphics/gpu/Extensions3DUtil.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef Extensions3DUtil_h
 #define Extensions3DUtil_h
 
 #include "platform/PlatformExport.h"
 #include "platform/graphics/GraphicsTypes3D.h"
 #include "third_party/khronos/GLES2/gl2.h"
 #include "third_party/khronos/GLES2/gl2ext.h"
 #include "wtf/HashSet.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
+
 class WebGraphicsContext3D;
-}
-
-namespace blink {
 
 class PLATFORM_EXPORT Extensions3DUtil {
 public:
     // Creates a new Extensions3DUtil. If the passed WebGraphicsContext3D has been spontaneously lost, returns null.
-    static PassOwnPtr<Extensions3DUtil> create(blink::WebGraphicsContext3D*);
+    static PassOwnPtr<Extensions3DUtil> create(WebGraphicsContext3D*);
     ~Extensions3DUtil();
 
     bool supportsExtension(const String& name);
     bool ensureExtensionEnabled(const String& name);
     bool isExtensionEnabled(const String& name);
 
     static bool canUseCopyTextureCHROMIUM(GLenum destFormat, GLenum destType, GLint level);
 
 private:
-    Extensions3DUtil(blink::WebGraphicsContext3D*);
+    Extensions3DUtil(WebGraphicsContext3D*);
     bool initializeExtensions();
 
-    blink::WebGraphicsContext3D* m_context;
+    WebGraphicsContext3D* m_context;
     HashSet<String> m_enabledExtensions;
     HashSet<String> m_requestableExtensions;
 };
 
 } // namespace blink
 
 #endif // Extensions3DUtil_h