Let the browser know the end of fling

content/renderer/input/input_handler_proxy.cc

Index: content/renderer/input/input_handler_proxy.cc
diff --git a/content/renderer/input/input_handler_proxy.cc b/content/renderer/input/input_handler_proxy.cc
index fa95881c2f1528239cb7f92f94a60e52d056d045..b66f5ac82b9f83745a27af2d3f1163131b48de3e 100644
--- a/content/renderer/input/input_handler_proxy.cc
+++ b/content/renderer/input/input_handler_proxy.cc
@@ -295,6 +295,7 @@ InputHandlerProxy::HandleGestureFling(
       fling_parameters_.modifiers = gesture_event.modifiers;
       fling_parameters_.sourceDevice = gesture_event.sourceDevice;
       input_handler_->ScheduleAnimation();
+      client_->DidStartFlinging();
       return DID_HANDLE;
     }
     case cc::InputHandler::ScrollOnMainThread: {
@@ -303,6 +304,7 @@ InputHandlerProxy::HandleGestureFling(
                            "scroll_on_main_thread",
                            TRACE_EVENT_SCOPE_THREAD);
       fling_may_be_active_on_main_thread_ = true;
+      client_->DidStartFlinging();

[jdduke (slow), 2014/01/10 17:45:59]

So, if the fling goes unhandled by main, the |DidStart()| will be terminated by
the NOT_CONSUMED ack? 

       return DID_NOT_HANDLE;
     }
     case cc::InputHandler::ScrollIgnored: {
@@ -352,6 +354,7 @@ void InputHandlerProxy::Animate(base::TimeTicks time) {
 
 void InputHandlerProxy::MainThreadHasStoppedFlinging() {
   fling_may_be_active_on_main_thread_ = false;
+  client_->DidStopFlinging();
 }
 
 void InputHandlerProxy::DidOverscroll(const cc::DidOverscrollParams& params) {
@@ -388,6 +391,8 @@ bool InputHandlerProxy::CancelCurrentFling() {
   fling_curve_.reset();
   gesture_scroll_on_impl_thread_ = false;
   fling_parameters_ = blink::WebActiveWheelFlingParameters();
+  if (had_fling_animation)
+    client_->DidStopFlinging();
   return had_fling_animation;
 }