Standardize usage of virtual/override/final in cc/

cc/trees/layer_tree_host_pixeltest_masks.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 "build/build_config.h"
 #include "cc/layers/content_layer_client.h"
 #include "cc/layers/picture_image_layer.h"
 #include "cc/layers/picture_layer.h"
 #include "cc/layers/solid_color_layer.h"
 #include "cc/test/layer_tree_pixel_test.h"
 #include "cc/test/pixel_comparator.h"
 
 #if !defined(OS_ANDROID)
 
 namespace cc {
 namespace {
 
 class LayerTreeHostMasksPixelTest : public LayerTreePixelTest {};
 
 class MaskContentLayerClient : public ContentLayerClient {
  public:
   explicit MaskContentLayerClient(const gfx::Size& bounds) : bounds_(bounds) {}
-  virtual ~MaskContentLayerClient() {}
+  ~MaskContentLayerClient() override {}
 
-  virtual void DidChangeLayerCanUseLCDText() override {}
+  void DidChangeLayerCanUseLCDText() override {}
 
-  virtual bool FillsBoundsCompletely() const override { return false; }
+  bool FillsBoundsCompletely() const override { return false; }
 
-  virtual void PaintContents(
+  void PaintContents(
       SkCanvas* canvas,
       const gfx::Rect& rect,
       ContentLayerClient::GraphicsContextStatus gc_status) override {
     SkPaint paint;
     paint.setStyle(SkPaint::kStroke_Style);
     paint.setStrokeWidth(SkIntToScalar(2));
     paint.setColor(SK_ColorWHITE);
 
     canvas->clear(SK_ColorTRANSPARENT);
     gfx::Rect inset_rect(bounds_);
@@ skipping 235 matching lines @@
   RunPixelTest(GL_WITH_BITMAP,
                background,
                base::FilePath(FILE_PATH_LITERAL(
                    "mask_of_replica_of_clipped_layer.png")));
 }
 
 }  // namespace
 }  // namespace cc
 
 #endif  // OS_ANDROID