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

content/browser/renderer_host/input/touch_event_queue.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/input/touch_event_queue.h"
 
 #include <utility>
 
 #include "base/auto_reset.h"
 #include "base/macros.h"
@@ skipping 774 matching lines @@
 
   touch_queue_.pop_front();
 }
 
 void TouchEventQueue::SendTouchEventImmediately(
     TouchEventWithLatencyInfo* touch) {
   // TODO(crbug.com/600773): Hack to avoid cyclic reentry to this method.
   if (dispatching_touch_)
     return;
 
+  if (touch->event.type == WebInputEvent::TouchStart)
+    touch->event.touchStartOrFirstTouchMove = true;
+
   // For touchmove events, compare touch points position from current event
   // to last sent event and update touch points state.
   if (touch->event.type == WebInputEvent::TouchMove) {
     CHECK(last_sent_touchevent_);
+    if (last_sent_touchevent_->type == WebInputEvent::TouchStart)
+      touch->event.touchStartOrFirstTouchMove = true;
     for (unsigned int i = 0; i < last_sent_touchevent_->touchesLength; ++i) {
       const WebTouchPoint& last_touch_point =
           last_sent_touchevent_->touches[i];
       // Touches with same id may not have same index in Touches array.
       for (unsigned int j = 0; j < touch->event.touchesLength; ++j) {
         const WebTouchPoint& current_touchmove_point = touch->event.touches[j];
         if (current_touchmove_point.id != last_touch_point.id)
           continue;
 
         if (!HasPointChanged(last_touch_point, current_touchmove_point))
@@ skipping 117 matching lines @@
     if (ack_result == INPUT_EVENT_ACK_STATE_CONSUMED)
       send_touch_events_async_ = false;
     has_handler_for_current_sequence_ |=
         ack_result != INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS;
   } else if (WebTouchEventTraits::IsTouchSequenceEnd(event)) {
     has_handler_for_current_sequence_ = false;
   }
 }
 
 }  // namespace content