Make first TouchStart and first TouchMove events on a flinging layer non-blocking

content/renderer/input/main_thread_event_queue.cc

Index: content/renderer/input/main_thread_event_queue.cc
diff --git a/content/renderer/input/main_thread_event_queue.cc b/content/renderer/input/main_thread_event_queue.cc
index ee2a34918d69a96861d89c6cf1935c2be2e93f48..232b7a65d51f15e7556ebd7ae75312371f28ed2b 100644
--- a/content/renderer/input/main_thread_event_queue.cc
+++ b/content/renderer/input/main_thread_event_queue.cc
@@ -57,10 +57,6 @@ bool MainThreadEventQueue::HandleEvent(
 
   bool non_blocking = original_dispatch_type == DISPATCH_TYPE_NON_BLOCKING ||
                       ack_result == INPUT_EVENT_ACK_STATE_SET_NON_BLOCKING;
-
-  InputEventDispatchType dispatch_type =
-      non_blocking ? DISPATCH_TYPE_NON_BLOCKING : DISPATCH_TYPE_BLOCKING;
-
   bool is_wheel = event->type == blink::WebInputEvent::MouseWheel;
   bool is_touch = blink::WebInputEvent::isTouchEventType(event->type);
 
@@ -74,6 +70,12 @@ bool MainThreadEventQueue::HandleEvent(
       touch_event->dispatchType =
           blink::WebInputEvent::ListenersNonBlockingPassive;
     }
+    if (is_flinging_ && touch_event->touchStartOrFirstTouchMove &&
+        touch_event->dispatchType == blink::WebInputEvent::Blocking) {
+      touch_event->dispatchType =
+          blink::WebInputEvent::ListenersForcedNonBlockingPassiveDueToFling;
+      non_blocking = true;
+    }
   }
   if (is_wheel && non_blocking) {
     // Adjust the |dispatchType| on the event since the compositor
@@ -82,6 +84,8 @@ bool MainThreadEventQueue::HandleEvent(
         ->dispatchType = blink::WebInputEvent::ListenersNonBlockingPassive;
   }
 
+  InputEventDispatchType dispatch_type =
+      non_blocking ? DISPATCH_TYPE_NON_BLOCKING : DISPATCH_TYPE_BLOCKING;
   std::unique_ptr<EventWithDispatchType> event_with_dispatch_type(
       new EventWithDispatchType(std::move(event), latency, dispatch_type));