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 b3053c0fe8ca091556cf2ae5ea19eefa6761bcea..2c28e88a193d21cc528856c1866d414491ff0f26 100644
--- a/cc/thread_proxy.cc
+++ b/cc/thread_proxy.cc
@@ -1235,4 +1235,15 @@ void ThreadProxy::renewTreePriorityOnImplThread()
     RenewTreePriority();
 }
 
+void ThreadProxy::RequestScrollbarAnimationOnImplThread(double delay) {
+  Proxy::ImplThread()->postDelayedTask(
+      base::Bind(&ThreadProxy::StartScrollbarAnimationOnImplThread,
+                 m_implThreadWeakPtr),
+      delay * 1000.0);
+}
+
+void ThreadProxy::StartScrollbarAnimationOnImplThread() {
+  m_layerTreeHostImpl->StartScrollbarAnimation(base::TimeTicks::Now());
+}
+
 }  // namespace cc