Add UMA for CrossFadeAnimation.

ash/rotator/screen_rotation_animator.cc

 // Copyright 2015 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 "ash/rotator/screen_rotation_animator.h"
 
 #include "ash/ash_switches.h"
 #include "ash/display/window_tree_host_manager.h"
 #include "ash/public/cpp/shell_window_ids.h"
 #include "ash/rotator/screen_rotation_animation.h"
@@ skipping 132 matching lines @@
   black_mask_layer->SetColor(SK_ColorBLACK);
   std::unique_ptr<ui::LayerOwner> black_mask_layer_owner =
       base::MakeUnique<ui::LayerOwner>();
   black_mask_layer_owner->SetLayer(std::move(black_mask_layer));
   return black_mask_layer_owner;
 }
 
 class ScreenRotationAnimationMetricsReporter
     : public ui::AnimationMetricsReporter {
  public:
-  ScreenRotationAnimationMetricsReporter() {}
-  ~ScreenRotationAnimationMetricsReporter() override {}
+  ScreenRotationAnimationMetricsReporter() = default;
+  ~ScreenRotationAnimationMetricsReporter() override = default;
 
   void Report(int value) override {
     UMA_HISTOGRAM_PERCENTAGE("Ash.Rotation.AnimationSmoothness", value);
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ScreenRotationAnimationMetricsReporter);
 };
 
 }  // namespace
@@ skipping 319 matching lines @@
   // the rotation request comes before the copy request finished.
   if (old_layer_tree_owner_)
     old_layer_tree_owner_->root()->GetAnimator()->StopAnimating();
   if (new_layer_tree_owner_)
     new_layer_tree_owner_->root()->GetAnimator()->StopAnimating();
   if (IsDisplayIdValid(display_id_) && black_mask_layer_owner_)
     root_window_->layer()->Remove(black_mask_layer_owner_->layer());
 }
 
 }  // namespace ash