Teach main thread event queue about closures.

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 "base/feature_list.h"
 #include "content/common/content_export.h"
 #include "content/common/input/input_event_ack_state.h"
 #include "content/common/input/input_event_dispatch_type.h"
 #include "content/common/input/web_input_event_queue.h"
 #include "content/public/common/content_features.h"
 #include "content/renderer/input/scoped_web_input_event_with_latency_info.h"
 #include "third_party/WebKit/public/platform/WebInputEvent.h"
 #include "third_party/WebKit/public/platform/scheduler/renderer/renderer_scheduler.h"
 #include "ui/events/blink/web_input_event_traits.h"
 #include "ui/events/latency_info.h"
 
 namespace content {
 
-class EventWithDispatchType : public ScopedWebInputEventWithLatencyInfo {
+class MainThreadEventQueueClient;
+
+class QueuedItem {

[mustaq, 2017/03/24 15:31:18]

Since this is an exposed class, I would prefer a more meaningful/focused name
than a generic |QueuedItem|. Is |MainThreadEventQueueItem| too long? Or simply
|MainThreadQueueItem|?

[dtapuska, 2017/03/24 20:16:34]

Done.

  public:
-  EventWithDispatchType(ui::WebScopedInputEvent event,
-                        const ui::LatencyInfo& latency,
-                        InputEventDispatchType dispatch_type,
-                        bool originally_cancelable);
-  ~EventWithDispatchType();
-  void CoalesceWith(const EventWithDispatchType& other);
+  virtual ~QueuedItem() {}
 
-  const std::deque<uint32_t>& blockingCoalescedEventIds() const {
-    return blocking_coalesced_event_ids_;
-  }
-  InputEventDispatchType dispatchType() const { return dispatch_type_; }
-  base::TimeTicks creationTimestamp() const { return creation_timestamp_; }
-  base::TimeTicks lastCoalescedTimestamp() const {
-    return last_coalesced_timestamp_;
-  }
-
-  size_t coalescedCount() const {
-    return non_blocking_coalesced_count_ + blocking_coalesced_event_ids_.size();
-  }
-
-  bool originallyCancelable() const { return originally_cancelable_; }
-
- private:
-  InputEventDispatchType dispatch_type_;
-
-  // Contains the unique touch event ids to be acked. If
-  // the events are not TouchEvents the values 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> blocking_coalesced_event_ids_;
-  // Contains the number of non-blocking events coalesced.
-  size_t non_blocking_coalesced_count_;
-  base::TimeTicks creation_timestamp_;
-  base::TimeTicks last_coalesced_timestamp_;
-
-  // Whether the received event was originally cancelable or not. The compositor
-  // input handler can change the event based on presence of event handlers so
-  // this is the state at which the renderer received the event from the
-  // browser.
-  bool originally_cancelable_;
+  virtual bool CanCoalesceWith(const QueuedItem&) = 0;
+  virtual void CoalesceWith(const QueuedItem&) = 0;
+  virtual bool IsSameEventClass(const QueuedItem&) const = 0;
+  virtual bool IsEvent() const = 0;
+  virtual void Dispatch(int routing_id, MainThreadEventQueueClient*) = 0;
+  virtual void EventHandled(
+      int routing_id,
+      blink::scheduler::RendererScheduler* renderer_scheduler,
+      MainThreadEventQueueClient* client,
+      blink::WebInputEvent::Type type,
+      blink::WebInputEventResult result,
+      InputEventAckState ack_result) = 0;
 };
 
 class CONTENT_EXPORT MainThreadEventQueueClient {
  public:
   // Handle an |event| that was previously queued (possibly
   // coalesced with another event) to the |routing_id|'s
   // channel. Implementors must implement this callback.
   virtual void HandleEventOnMainThread(
       int routing_id,
       const blink::WebCoalescedInputEvent* event,
@@ skipping 52 matching lines @@
       const scoped_refptr<base::SingleThreadTaskRunner>& main_task_runner,
       blink::scheduler::RendererScheduler* renderer_scheduler);
 
   // Called once the compositor has handled |event| and indicated that it is
   // a non-blocking event to be queued to the main thread.
   bool HandleEvent(ui::WebScopedInputEvent event,
                    const ui::LatencyInfo& latency,
                    InputEventDispatchType dispatch_type,
                    InputEventAckState ack_result);
   void DispatchRafAlignedInput(base::TimeTicks frame_time);
+  void QueueClosure(const base::Closure& closure);
 
   // Call once the main thread has handled an outstanding |type| event
   // in flight.
   void EventHandled(blink::WebInputEvent::Type type,
                     blink::WebInputEventResult result,
                     InputEventAckState ack_result);
 
  private:
   friend class base::RefCountedThreadSafe<MainThreadEventQueue>;
   ~MainThreadEventQueue();
-  void QueueEvent(std::unique_ptr<EventWithDispatchType> event);
+  void QueueEvent(std::unique_ptr<QueuedItem> event);
   void SendEventNotificationToMainThread();
-  void DispatchSingleEvent();
+  void DispatchEvents();
   void DispatchInFlightEvent();
   void PossiblyScheduleMainFrame();
 
   void SendEventToMainThread(const blink::WebInputEvent* event,
                              const ui::LatencyInfo& latency,
                              InputEventDispatchType original_dispatch_type);
 
-  bool IsRafAlignedInputDisabled();
-  bool IsRafAlignedEvent(const blink::WebInputEvent& event);
+  bool IsRafAlignedInputDisabled() const;
+  bool IsRafAlignedEvent(const std::unique_ptr<QueuedItem>& item) const;

[mustaq, 2017/03/24 15:31:18]

This seems to belong to the class |QueuedItem| (|MainThreadQueueItem|)?

[dtapuska, 2017/03/24 20:16:34]

I agree. But it needs to check the variables stored on this class. How do you
think we should fetch the state variables?

 
   friend class MainThreadEventQueueTest;
   friend class MainThreadEventQueueInitializationTest;
   int routing_id_;
   MainThreadEventQueueClient* client_;
-  std::unique_ptr<EventWithDispatchType> in_flight_event_;
+  std::unique_ptr<QueuedItem> in_flight_event_;
   bool last_touch_start_forced_nonblocking_due_to_fling_;
   bool enable_fling_passive_listener_flag_;
   bool enable_non_blocking_due_to_main_thread_responsiveness_flag_;
   base::TimeDelta main_thread_responsiveness_threshold_;
   bool handle_raf_aligned_touch_input_;
   bool handle_raf_aligned_mouse_input_;
 
   // Contains data to be shared between main thread and compositor thread.
   struct SharedState {
     SharedState();
     ~SharedState();
 
-    WebInputEventQueue<EventWithDispatchType> events_;
+    WebInputEventQueue<QueuedItem> events_;
     bool sent_main_frame_request_;
+    bool sent_post_task_;

[mustaq, 2017/03/24 15:31:18]

Could you please clarify what "sent" means here, through a comment perhaps? The
time-span ("sent" since which point in time) is not clear to me.

[dtapuska, 2017/03/24 20:16:34]

Done.

     base::TimeTicks last_async_touch_move_timestamp_;
   };
 
   // Lock used to serialize |shared_state_|.
   base::Lock shared_state_lock_;
   SharedState shared_state_;
 
   scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
   blink::scheduler::RendererScheduler* renderer_scheduler_;
 
   DISALLOW_COPY_AND_ASSIGN(MainThreadEventQueue);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_INPUT_MAIN_THREAD_EVENT_QUEUE_H_