Fix virtual/override/final usage in Source/core/layout/.

Source/core/layout/LayoutTestHelper.cpp

 // 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.
 
 #include "config.h"
 #include "core/layout/LayoutTestHelper.h"
 
 #include "core/loader/EmptyClients.h"
 #include "platform/graphics/GraphicsLayer.h"
 #include "platform/graphics/GraphicsLayerFactory.h"
 
 namespace blink {
 
 class FakeGraphicsLayerFactory : public GraphicsLayerFactory {
 public:
-    virtual PassOwnPtr<GraphicsLayer> createGraphicsLayer(GraphicsLayerClient* client) override
+    PassOwnPtr<GraphicsLayer> createGraphicsLayer(GraphicsLayerClient* client) override
     {
         return adoptPtr(new GraphicsLayer(client));
     }
 };
 
 class FakeChromeClient : public EmptyChromeClient {
 public:
     virtual GraphicsLayerFactory* graphicsLayerFactory() const
     {
         static FakeGraphicsLayerFactory* factory = adoptPtr(new FakeGraphicsLayerFactory).leakPtr();
         return factory;
     }
 };
 
 void RenderingTest::SetUp()
 {
     fillWithEmptyClients(m_pageClients);
     static FakeChromeClient* chromeClient = adoptPtr(new FakeChromeClient).leakPtr();
     m_pageClients.chromeClient = chromeClient;
     m_pageHolder = DummyPageHolder::create(IntSize(800, 600), &m_pageClients);
 
     // This ensures that the minimal DOM tree gets attached
     // correctly for tests that don't call setBodyInnerHTML.
     document().view()->updateAllLifecyclePhases();
 }
 
 
 } // namespace blink