Teach main thread event queue about closures.

content/renderer/input/main_thread_event_queue.h

Index: content/renderer/input/main_thread_event_queue.h
diff --git a/content/renderer/input/main_thread_event_queue.h b/content/renderer/input/main_thread_event_queue.h
index c793bdd7efcc0a2b0fc580f5095e61eb3cba3f93..538e6177ac2e7493134815c9dd1312abe515b261 100644
--- a/content/renderer/input/main_thread_event_queue.h
+++ b/content/renderer/input/main_thread_event_queue.h
@@ -20,48 +20,24 @@
 
 namespace content {
 
-class EventWithDispatchType : public ScopedWebInputEventWithLatencyInfo {
- public:
-  EventWithDispatchType(ui::WebScopedInputEvent event,
-                        const ui::LatencyInfo& latency,
-                        InputEventDispatchType dispatch_type,
-                        bool originally_cancelable);
-  ~EventWithDispatchType();
-  void CoalesceWith(const EventWithDispatchType& other);
-
-  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_; }
+class MainThreadEventQueueClient;
 
- 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_;
+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:
+  virtual ~QueuedItem() {}
+
+  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 {
@@ -134,6 +110,7 @@ class CONTENT_EXPORT MainThreadEventQueue
                    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.
@@ -144,9 +121,9 @@ class CONTENT_EXPORT MainThreadEventQueue
  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();
 
@@ -154,14 +131,14 @@ class CONTENT_EXPORT MainThreadEventQueue
                              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_;
@@ -174,8 +151,9 @@ class CONTENT_EXPORT MainThreadEventQueue
     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_;
   };