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 772d3be1c6bc31a979561586ac353b966ba1780a..84b340ef0b450ada334b7023ca2a630c079ae1cc 100644
--- a/content/renderer/input/main_thread_event_queue.cc
+++ b/content/renderer/input/main_thread_event_queue.cc
@@ -41,7 +41,8 @@ MainThreadEventQueue::MainThreadEventQueue(
     : routing_id_(routing_id),
       client_(client),
       is_flinging_(false),
-      main_task_runner_(main_task_runner) {}
+      main_task_runner_(main_task_runner),
+      waiting_for_first_touch_move_(false) {}
 
 MainThreadEventQueue::~MainThreadEventQueue() {}
 
@@ -71,12 +72,28 @@ bool MainThreadEventQueue::HandleEvent(
     blink::WebTouchEvent& touch_event =
         static_cast<blink::WebTouchEvent&>(cloned_event->event());
     touch_event.dispatchedDuringFling = is_flinging_;
+    bool touch_start_or_first_touch_move = false;
+    if (event->type == blink::WebInputEvent::TouchStart) {
+      waiting_for_first_touch_move_ = true;
+      touch_start_or_first_touch_move = true;
+    } else if (event->type == blink::WebInputEvent::TouchMove) {
+      touch_start_or_first_touch_move = waiting_for_first_touch_move_;
+      waiting_for_first_touch_move_ = false;
+    }
+    touch_event.touchStartOrFirstTouchMove = touch_start_or_first_touch_move;

[dtapuska, 2016/08/12 14:40:00]

Why is this populated here? Can't it be sent from the touch_event_queue? then it
will be correct when the compositor deals with the events.

     // Adjust the |dispatchType| on the event since the compositor
     // determined all event listeners are passive.
     if (non_blocking) {
       touch_event.dispatchType =
           blink::WebInputEvent::ListenersNonBlockingPassive;
     }
+    if (is_flinging_ && touch_start_or_first_touch_move &&
+        touch_event.dispatchType == blink::WebInputEvent::Blocking) {
+      touch_event.dispatchType =
+          blink::WebInputEvent::ListenersForcedNonBlockingPassiveDueToFling;
+      cloned_event->setDispatchType(DISPATCH_TYPE_NON_BLOCKING);
+      non_blocking = true;
+    }
   }
   if (is_wheel && non_blocking) {
     // Adjust the |dispatchType| on the event since the compositor