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

Source/platform/graphics/Canvas2DLayerBridge.h

Index: Source/platform/graphics/Canvas2DLayerBridge.h
diff --git a/Source/platform/graphics/Canvas2DLayerBridge.h b/Source/platform/graphics/Canvas2DLayerBridge.h
index 4194711597304e4aee90d10f1c1dc20d176000b9..9c6653b15909793654e816830ff81049407a91ee 100644
--- a/Source/platform/graphics/Canvas2DLayerBridge.h
+++ b/Source/platform/graphics/Canvas2DLayerBridge.h
@@ -53,17 +53,17 @@ class PLATFORM_EXPORT Canvas2DLayerBridge : public WebExternalTextureLayerClient
 public:
     static PassRefPtr<Canvas2DLayerBridge> create(const IntSize&, OpacityMode, int msaaSampleCount);
 
-    virtual ~Canvas2DLayerBridge();
+    ~Canvas2DLayerBridge() override;
 
     // WebExternalTextureLayerClient implementation.
-    virtual bool prepareMailbox(WebExternalTextureMailbox*, WebExternalBitmap*) override;
-    virtual void mailboxReleased(const WebExternalTextureMailbox&, bool lostResource) override;
+    bool prepareMailbox(WebExternalTextureMailbox*, WebExternalBitmap*) override;
+    void mailboxReleased(const WebExternalTextureMailbox&, bool lostResource) override;
 
     // SkDeferredCanvas::NotificationClient implementation
-    virtual void prepareForDraw() override;
-    virtual void storageAllocatedForRecordingChanged(size_t) override;
-    virtual void flushedDrawCommands() override;
-    virtual void skippedPendingDrawCommands() override;
+    void prepareForDraw() override;
+    void storageAllocatedForRecordingChanged(size_t) override;
+    void flushedDrawCommands() override;
+    void skippedPendingDrawCommands() override;
 
     // ImageBufferSurface implementation
     void finalizeFrame(const FloatRect &dirtyRect);