[animations] Adds metrics for jank on selected layer animations

ui/compositor/layer_animator.h

 // Copyright (c) 2012 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.
 
 #ifndef UI_COMPOSITOR_LAYER_ANIMATOR_H_
 #define UI_COMPOSITOR_LAYER_ANIMATOR_H_
 
 #include <deque>
 #include <vector>
 
@@ skipping 344 matching lines @@
       double animation_start_time,
       std::unique_ptr<cc::AnimationCurve> curve) override {}
 
   // Implementation of LayerThreadedAnimationDelegate.
   void AddThreadedAnimation(std::unique_ptr<cc::Animation> animation) override;
   void RemoveThreadedAnimation(int animation_id) override;
 
   void AttachLayerToAnimationPlayer(int layer_id);
   void DetachLayerFromAnimationPlayer();
 
+  void set_animation_metrics_reporter(AnimationMetricsReporter* reporter) {
+    animation_metrics_reporter_ = reporter;
+  }
+
   // This is the queue of animations to run.
   AnimationQueue animation_queue_;
 
   // The target of all layer animations.
   LayerAnimationDelegate* delegate_;
 
   // Plays CC animations.
   scoped_refptr<cc::AnimationPlayer> animation_player_;
 
   // The currently running animations.
@@ skipping 19 matching lines @@
   bool is_started_;
 
   // This prevents the animator from automatically stepping through animations
   // and allows for manual stepping.
   bool disable_timer_for_test_;
 
   // Prevents timer adjustments in case when we start multiple animations
   // with preemption strategies that discard previous animations.
   bool adding_animations_;
 
+  // Helper to output UMA performance metrics.
+  AnimationMetricsReporter* animation_metrics_reporter_;
+
   // Observers are notified when layer animations end, are scheduled or are
   // aborted.
   base::ObserverList<LayerAnimationObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerAnimator);
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_LAYER_ANIMATOR_H_