Fix virtual/override/final usage in Source/platform/.

Source/platform/graphics/ImageFrameGenerator.cpp

 /*
  * 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 27 matching lines @@
 // This is used to write directly to the memory given by Skia during decoding.
 class ImageFrameGenerator::ExternalMemoryAllocator : public SkBitmap::Allocator {
 public:
     ExternalMemoryAllocator(const SkImageInfo& info, void* pixels, size_t rowBytes)
         : m_info(info)
         , m_pixels(pixels)
         , m_rowBytes(rowBytes)
     {
     }
 
-    virtual bool allocPixelRef(SkBitmap* dst, SkColorTable* ctable) override
+    bool allocPixelRef(SkBitmap* dst, SkColorTable* ctable) override
     {
         const SkImageInfo& info = dst->info();
         if (kUnknown_SkColorType == info.colorType())
             return false;
 
         if (info != m_info || m_rowBytes != dst->rowBytes())
             return false;
 
         if (!dst->installPixels(m_info, m_pixels, m_rowBytes))
             return false;
@@ skipping 297 matching lines @@
 
     // Setting a dummy ImagePlanes object signals to the decoder that we want to do YUV decoding.
     decoder->setData(data, allDataReceived);
     OwnPtr<ImagePlanes> dummyImagePlanes = adoptPtr(new ImagePlanes);
     decoder->setImagePlanes(dummyImagePlanes.release());
 
     return updateYUVComponentSizes(decoder.get(), componentSizes, ImageDecoder::SizeForMemoryAllocation);
 }
 
 } // namespace blink