MouseWheelEventQueue should respect ScrollBegin/End state from RenderWidgetHost.

content/browser/renderer_host/input/mock_input_router_client.cc

Index: content/browser/renderer_host/input/mock_input_router_client.cc
diff --git a/content/browser/renderer_host/input/mock_input_router_client.cc b/content/browser/renderer_host/input/mock_input_router_client.cc
index 2a3cde0700029e7e19db2d06e338e4bd7088a1bd..09d33858a77c1f6b3661cc0abd489d1c8bfb3f41 100644
--- a/content/browser/renderer_host/input/mock_input_router_client.cc
+++ b/content/browser/renderer_host/input/mock_input_router_client.cc
@@ -22,10 +22,10 @@ MockInputRouterClient::MockInputRouterClient()
     : input_router_(NULL),
       in_flight_event_count_(0),
       has_touch_handler_(false),
+      is_in_gesture_scroll_(false),
       filter_state_(INPUT_EVENT_ACK_STATE_NOT_CONSUMED),
       filter_input_event_called_(false),
-      did_flush_called_count_(0) {
-}
+      did_flush_called_count_(0) {}
 
 MockInputRouterClient::~MockInputRouterClient() {}
 
@@ -70,6 +70,19 @@ void MockInputRouterClient::ForwardGestureEventWithLatencyInfo(
   if (input_router_)
     input_router_->SendGestureEvent(
         GestureEventWithLatencyInfo(gesture_event, latency_info));
+  if (gesture_event.GetType() == blink::WebInputEvent::kGestureScrollBegin &&
+      !gesture_event.data.scroll_begin.synthetic) {
+    is_in_gesture_scroll_ = true;
+  } else if (gesture_event.GetType() ==
+                 blink::WebInputEvent::kGestureScrollEnd &&
+             !gesture_event.data.scroll_end.synthetic) {
+    is_in_gesture_scroll_ = false;
+  }
+}
+
+bool MockInputRouterClient::IsInGestureScroll(
+    blink::WebGestureDevice device) const {
+  return is_in_gesture_scroll_;
 }
 
 bool MockInputRouterClient::GetAndResetFilterEventCalled() {