Update from https://crrev.com/309717

cc/animation/scrollbar_animation_controller_thinning_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/animation/scrollbar_animation_controller_thinning.h"
 
 #include "cc/layers/solid_color_scrollbar_layer_impl.h"
 #include "cc/test/fake_impl_proxy.h"
 #include "cc/test/fake_layer_tree_host_impl.h"
 #include "cc/test/geometry_test_utils.h"
@@ skipping 11 matching lines @@
   ScrollbarAnimationControllerThinningTest()
       : host_impl_(&proxy_, &shared_bitmap_manager_) {}
 
   void PostDelayedScrollbarFade(const base::Closure& start_fade,
                                 base::TimeDelta delay) override {
     start_fade_ = start_fade;
   }
   void SetNeedsScrollbarAnimationFrame() override {}
 
  protected:
-  virtual void SetUp() {
+  void SetUp() override {
     scoped_ptr<LayerImpl> scroll_layer =
         LayerImpl::Create(host_impl_.active_tree(), 1);
     clip_layer_ = LayerImpl::Create(host_impl_.active_tree(), 3);
     scroll_layer->SetScrollClipLayer(clip_layer_->id());
     LayerImpl* scroll_layer_ptr = scroll_layer.get();
     clip_layer_->AddChild(scroll_layer.Pass());
 
     const int kId = 2;
     const int kThumbThickness = 10;
     const int kTrackStart = 0;
@@ skipping 322 matching lines @@
 
   time += base::TimeDelta::FromSeconds(1);
   scrollbar_controller_->Animate(time);
   EXPECT_FLOAT_EQ(0.7f, scrollbar_layer_->opacity());
   // The thickness now gets big again.
   EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
 }
 
 }  // namespace
 }  // namespace cc