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

content/browser/renderer_host/input/legacy_touch_event_queue.h

 // 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.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_INPUT_LEGACY_TOUCH_EVENT_QUEUE_H_
 #define CONTENT_BROWSER_RENDERER_HOST_INPUT_LEGACY_TOUCH_EVENT_QUEUE_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 67 matching lines @@
   // Sets whether the current site has a mobile friendly viewport. This
   // determines which ack timeout delay will be used for *future* touch events.
   // The default assumption is that the site is *not* mobile-optimized.
   void SetIsMobileOptimizedSite(bool mobile_optimized_site) override;
 
   // Whether ack timeout behavior is supported and enabled for the current site.
   bool IsAckTimeoutEnabled() const override;
 
   bool Empty() const override;
 
+  bool SendTouchEventsAsync() const override;
+
   bool empty() const WARN_UNUSED_RESULT { return Empty(); }
 
   size_t size() const { return touch_queue_.size(); }
 
   bool has_handlers() const { return has_handlers_; }
 
   size_t uncancelable_touch_moves_pending_ack_count() const {
     return ack_pending_async_touchmove_ids_.size();
   }
 
@@ skipping 103 matching lines @@
 
   // Event is saved to compare pointer positions for new touchmove events.
   std::unique_ptr<blink::WebTouchEvent> last_sent_touchevent_;
 
   DISALLOW_COPY_AND_ASSIGN(LegacyTouchEventQueue);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_INPUT_LEGACY_TOUCH_EVENT_QUEUE_H_