Clean up forward declarations in Source/platform

Source/platform/graphics/ImageFrameGenerator.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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 24 matching lines @@
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefCounted.h"
 #include "wtf/RefPtr.h"
 #include "wtf/ThreadingPrimitives.h"
 #include "wtf/ThreadSafeRefCounted.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 class ImageDecoder;
-class ImagePlanes;
 class SharedBuffer;
 
 class PLATFORM_EXPORT ImageDecoderFactory {
     WTF_MAKE_NONCOPYABLE(ImageDecoderFactory);
 public:
     ImageDecoderFactory() {}
     virtual ~ImageDecoderFactory() { }
     virtual PassOwnPtr<ImageDecoder> create() = 0;
 };
 
@@ skipping 61 matching lines @@
     // Prevents multiple decode operations on the same data.
     Mutex m_decodeMutex;
 
     // Protect concurrent access to m_hasAlpha.
     Mutex m_alphaMutex;
 };
 
 } // namespace blink
 
 #endif