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

Source/platform/graphics/gpu/DrawingBuffer.h

 /*
  * Copyright (c) 2010, 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 77 matching lines @@
     };
 public:
     enum PreserveDrawingBuffer {
         Preserve,
         Discard
     };
 
     static PassRefPtr<DrawingBuffer> create(PassOwnPtr<WebGraphicsContext3D>, const IntSize&, PreserveDrawingBuffer, WebGraphicsContext3D::Attributes requestedAttributes);
     static void forceNextDrawingBufferCreationToFail();
 
-    virtual ~DrawingBuffer();
+    ~DrawingBuffer() override;
 
     // Destruction will be completed after all mailboxes are released.
     void beginDestruction();
 
     // Issues a glClear() on all framebuffers associated with this DrawingBuffer. The caller is responsible for
     // making the context current and setting the clear values and masks. Modifies the framebuffer binding.
     void clearFramebuffers(GLbitfield clearMask);
 
     // Given the desired buffer size, provides the largest dimensions that will fit in the pixel budget.
     static IntSize adjustSize(const IntSize& desiredSize, const IntSize& curSize, int maxTextureSize);
@@ skipping 51 matching lines @@
 
     WebLayer* platformLayer();
 
     WebGraphicsContext3D* context();
 
     // Returns the actual context attributes for this drawing buffer which may differ from the
     // requested context attributes due to implementation limits.
     WebGraphicsContext3D::Attributes getActualAttributes() const { return m_actualAttributes; }
 
     // WebExternalTextureLayerClient implementation.
-    virtual bool prepareMailbox(WebExternalTextureMailbox*, WebExternalBitmap*) override;
-    virtual void mailboxReleased(const WebExternalTextureMailbox&, bool lostResource = false) override;
+    bool prepareMailbox(WebExternalTextureMailbox*, WebExternalBitmap*) override;
+    void mailboxReleased(const WebExternalTextureMailbox&, bool lostResource = false) override;
 
     // Destroys the TEXTURE_2D binding for the owned context
     bool copyToPlatformTexture(WebGraphicsContext3D*, Platform3DObject texture, GLenum internalFormat,
         GLenum destType, GLint level, bool premultiplyAlpha, bool flipY, SourceDrawingBuffer);
 
     void setPackAlignment(GLint param);
 
     void paintRenderingResultsToCanvas(ImageBuffer*);
     bool paintRenderingResultsToImageData(int&, int&, SourceDrawingBuffer, WTF::ArrayBufferContents&);
 
@@ skipping 132 matching lines @@
     // used to resize the Canvas.
     SkBitmap m_resizingBitmap;
 
     // Used to flip a bitmap vertically.
     Vector<uint8_t> m_scanline;
 };
 
 } // namespace blink
 
 #endif // DrawingBuffer_h