[VSync Queue] Plug touch ack to gesture events and flush vsync queue if necessary

content/browser/renderer_host/input/input_router_impl.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/input_router_impl.h"
 
 #include <math.h>
 
 #include <utility>
 
@@ skipping 170 matching lines @@
     } else if (!touch_scroll_started_sent_ &&
                gesture_event.event.GetType() ==
                    blink::WebInputEvent::kGestureScrollUpdate) {
       // A touch scroll hasn't really started until the first
       // GestureScrollUpdate event.  Eg. if the page consumes all touchmoves
       // then no scrolling really ever occurs (even though we still send
       // GestureScrollBegin).
       touch_scroll_started_sent_ = true;
       touch_event_queue_->PrependTouchScrollNotification();
     }
+    gesture_event.event.source_touch_event_dispatch_type =
+        touch_event_queue_->SendTouchEventsAsync()

[dtapuska, 2017/05/10 14:49:00]

I don't think we really should query the state here. But instead use the ack
result of the message to determine if we should send the gesture as blocking or
not.

[chongz, 2017/05/24 13:47:09]

Done.

+            ? WebInputEvent::kEventNonBlocking
+            : WebInputEvent::kBlocking;
     touch_event_queue_->OnGestureScrollEvent(gesture_event);
   }
 
   gesture_event_queue_.QueueEvent(gesture_event);
 }
 
 void InputRouterImpl::SendTouchEvent(
     const TouchEventWithLatencyInfo& touch_event) {
   TouchEventWithLatencyInfo updatd_touch_event = touch_event;
   SetMovementXYForTouchPoints(&updatd_touch_event.event);
@@ skipping 468 matching lines @@
         DCHECK(global_touch_position_.find(touch_point->id) ==
                global_touch_position_.end());
         global_touch_position_[touch_point->id] = gfx::Point(
             touch_point->screen_position.x, touch_point->screen_position.y);
       }
     }
   }
 }
 
 }  // namespace content