Update from https://crrev.com/318214

cc/animation/scrollbar_animation_controller.cc

Index: cc/animation/scrollbar_animation_controller.cc
diff --git a/cc/animation/scrollbar_animation_controller.cc b/cc/animation/scrollbar_animation_controller.cc
index ffb22870825618a4a9e6e4bff1b58c5eeebb0c1e..48b199d6e665388e0021dd80dd4c97f84c5a5d4f 100644
--- a/cc/animation/scrollbar_animation_controller.cc
+++ b/cc/animation/scrollbar_animation_controller.cc
@@ -7,15 +7,18 @@
 #include <algorithm>
 
 #include "base/time/time.h"
+#include "cc/trees/layer_tree_impl.h"
 
 namespace cc {
 
 ScrollbarAnimationController::ScrollbarAnimationController(
+    LayerImpl* scroll_layer,
     ScrollbarAnimationControllerClient* client,
     base::TimeDelta delay_before_starting,
     base::TimeDelta resize_delay_before_starting,
     base::TimeDelta duration)
-    : client_(client),
+    : scroll_layer_(scroll_layer),
+      client_(client),
       delay_before_starting_(delay_before_starting),
       resize_delay_before_starting_(resize_delay_before_starting),
       duration_(duration),
@@ -26,6 +29,8 @@ ScrollbarAnimationController::ScrollbarAnimationController(
 }
 
 ScrollbarAnimationController::~ScrollbarAnimationController() {
+  if (is_animating_)
+    client_->StopAnimatingScrollbarAnimationController(this);
 }
 
 void ScrollbarAnimationController::Animate(base::TimeTicks now) {
@@ -37,11 +42,6 @@ void ScrollbarAnimationController::Animate(base::TimeTicks now) {
 
   float progress = AnimationProgressAtTime(now);
   RunAnimationFrame(progress);
-
-  if (is_animating_) {
-    delayed_scrollbar_fade_.Cancel();
-    client_->SetNeedsScrollbarAnimationFrame();
-  }
 }
 
 float ScrollbarAnimationController::AnimationProgressAtTime(
@@ -62,38 +62,40 @@ void ScrollbarAnimationController::DidScrollUpdate(bool on_resize) {
   // As an optimization, we avoid spamming fade delay tasks during active fast
   // scrolls.  But if we're not within one, we need to post every scroll update.
   if (!currently_scrolling_)
-    PostDelayedFade(on_resize);
+    PostDelayedAnimationTask(on_resize);
   else
     scroll_gesture_has_scrolled_ = true;
 }
 
 void ScrollbarAnimationController::DidScrollEnd() {
   if (scroll_gesture_has_scrolled_) {
-    PostDelayedFade(false);
+    PostDelayedAnimationTask(false);
     scroll_gesture_has_scrolled_ = false;
   }
 
   currently_scrolling_ = false;
 }
 
-void ScrollbarAnimationController::PostDelayedFade(bool on_resize) {
+void ScrollbarAnimationController::PostDelayedAnimationTask(bool on_resize) {
   base::TimeDelta delay =
       on_resize ? resize_delay_before_starting_ : delay_before_starting_;
   delayed_scrollbar_fade_.Reset(
       base::Bind(&ScrollbarAnimationController::StartAnimation,
                  weak_factory_.GetWeakPtr()));
-  client_->PostDelayedScrollbarFade(delayed_scrollbar_fade_.callback(), delay);
+  client_->PostDelayedScrollbarAnimationTask(delayed_scrollbar_fade_.callback(),
+                                             delay);
 }
 
 void ScrollbarAnimationController::StartAnimation() {
   delayed_scrollbar_fade_.Cancel();
   is_animating_ = true;
   last_awaken_time_ = base::TimeTicks();
-  client_->SetNeedsScrollbarAnimationFrame();
+  client_->StartAnimatingScrollbarAnimationController(this);
 }
 
 void ScrollbarAnimationController::StopAnimation() {
   is_animating_ = false;
+  client_->StopAnimatingScrollbarAnimationController(this);
 }
 
 }  // namespace cc