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

content/renderer/input/main_thread_event_queue.h

 // Copyright 2016 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_RENDERER_INPUT_MAIN_THREAD_EVENT_QUEUE_H_
 #define CONTENT_RENDERER_INPUT_MAIN_THREAD_EVENT_QUEUE_H_
 
 #include <deque>
 #include "content/common/content_export.h"
 #include "content/common/input/event_with_latency_info.h"
@@ skipping 11 matching lines @@
   EventWithDispatchType(const blink::WebInputEvent& event,
                         const ui::LatencyInfo& latency,
                         InputEventDispatchType dispatch_type);
   ~EventWithDispatchType();
   bool CanCoalesceWith(const EventWithDispatchType& other) const
       WARN_UNUSED_RESULT;
   void CoalesceWith(const EventWithDispatchType& other);
 
   const std::deque<uint32_t>& eventsToAck() const { return eventsToAck_; }
   InputEventDispatchType dispatchType() const { return dispatch_type_; }
+  void setDispatchType(InputEventDispatchType dispatch_type) {
+    dispatch_type_ = dispatch_type;
+  }
 
  private:
   InputEventDispatchType dispatch_type_;
 
   // |eventsToAck_| contains the unique touch event id to be acked. If
   // the events are TouchEvents the value will be 0. More importantly for
   // those cases the deque ends up containing how many additional ACKs
   // need to be sent.
   std::deque<uint32_t> eventsToAck_;
 };
@@ skipping 85 matching lines @@
 
   friend class MainThreadEventQueueTest;
   int routing_id_;
   MainThreadEventQueueClient* client_;
   WebInputEventQueue<EventWithDispatchType> events_;
   std::unique_ptr<EventWithDispatchType> in_flight_event_;
   bool is_flinging_;
 
   base::Lock event_queue_lock_;
   scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
+  // True if waiting on first touch move after a touch start.
+  bool waiting_for_first_touch_move_;
 
   DISALLOW_COPY_AND_ASSIGN(MainThreadEventQueue);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_INPUT_MAIN_THREAD_EVENT_QUEUE_H_