cc: Delay start of scrollbar animation setNeedsRedraw.

cc/thread_proxy.cc

Index: cc/thread_proxy.cc
diff --git a/cc/thread_proxy.cc b/cc/thread_proxy.cc
index 6c10d482511b90932aa69aa90b97b6d844d8acd7..367e47489daa0b49623abb66ea3d75a8cb4f5357 100644
--- a/cc/thread_proxy.cc
+++ b/cc/thread_proxy.cc
@@ -1316,7 +1316,7 @@ void ThreadProxy::RenewTreePriority() {
   Proxy::ImplThread()->postDelayedTask(
       base::Bind(&ThreadProxy::RenewTreePriorityOnImplThread,
                  weak_factory_on_impl_thread_.GetWeakPtr()),
-      delay.InMilliseconds());
+      delay);
 
   renew_tree_priority_on_impl_thread_pending_ = true;
 }
@@ -1328,4 +1328,15 @@ void ThreadProxy::RenewTreePriorityOnImplThread() {
   RenewTreePriority();
 }
 
+void ThreadProxy::RequestScrollbarAnimationOnImplThread(base::TimeDelta delay) {
+  Proxy::ImplThread()->postDelayedTask(
+      base::Bind(&ThreadProxy::StartScrollbarAnimationOnImplThread,
+                 impl_thread_weak_ptr_),
+      delay);
+}
+
+void ThreadProxy::StartScrollbarAnimationOnImplThread() {
+  layer_tree_host_impl_->StartScrollbarAnimation(base::TimeTicks::Now());
+}
+
 }  // namespace cc