Standardize usage of virtual/override/final specifiers in cc/.

cc/layers/picture_layer_impl_unittest.cc

 // Copyright 2013 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 "cc/layers/picture_layer_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <set>
 #include <utility>
@@ skipping 68 matching lines @@
   }
 
   explicit PictureLayerImplTest(const LayerTreeSettings& settings)
       : proxy_(base::MessageLoopProxy::current()),
         host_impl_(settings, &proxy_, &shared_bitmap_manager_),
         root_id_(6),
         id_(7) {
     host_impl_.SetViewportSize(gfx::Size(10000, 10000));
   }
 
-  virtual ~PictureLayerImplTest() {
-  }
+  ~PictureLayerImplTest() override {}
 
   void SetUp() override { InitializeRenderer(); }
 
   virtual void InitializeRenderer() {
     host_impl_.InitializeRenderer(FakeOutputSurface::Create3d());
   }
 
   void SetupDefaultTrees(const gfx::Size& layer_bounds) {
     gfx::Size tile_size(100, 100);
 
@@ skipping 4632 matching lines @@
   result = layer->CalculateTileSize(gfx::Size(447, 400));
   EXPECT_EQ(result.width(), 448);
   EXPECT_EQ(result.height(), 448);
   result = layer->CalculateTileSize(gfx::Size(500, 499));
   EXPECT_EQ(result.width(), 512);
   EXPECT_EQ(result.height(), 500 + 2);
 }
 
 }  // namespace
 }  // namespace cc