Ensure acks are sent for all blocking events.

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"
 #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 "third_party/WebKit/public/web/WebInputEvent.h"
 #include "ui/events/latency_info.h"
 
 namespace content {
 
 template <typename BaseClass, typename BaseType>
 class EventWithDispatchType : public BaseClass {

[tdresser, 2016/06/28 14:04:49]

This name is becoming less and less accurate over time - probably fine for now
though.

[dtapuska, 2016/06/28 17:30:21]

Acknowledged.

  public:
   EventWithDispatchType(const BaseType& e,
                         const ui::LatencyInfo& l,
                         InputEventDispatchType t)
       : BaseClass(e, l), type(t) {}
 
   InputEventDispatchType type;
+  std::deque<uint32_t> eventsToAck;

[tdresser, 2016/06/28 14:04:49]

touchEventIdsToAck?

For wheel, we just need a count of the number of acks to send. Using a list of
zeros for a count is a bit weird - we should either split it up and have a
separate count for touchpad, or at least add a comment stating that for
touchpad, this is just an deque of zeros.

[dtapuska, 2016/06/28 17:30:21]

I've changed it to be a dcheck for wheel events.

 
   bool CanCoalesceWith(const EventWithDispatchType& other) const
       WARN_UNUSED_RESULT {
     return other.type == type && BaseClass::CanCoalesceWith(other);
   }
 
   void CoalesceWith(const EventWithDispatchType& other) {
+    // If we are blocking; and are coalescing touch; make sure to keep

[tdresser, 2016/06/28 14:04:49]

Nit: I think these ; are being used incorrectly - maybe just use ,'s?

[dtapuska, 2016/06/28 17:30:21]

Done.

+    // the touch ids that need to be acked.
+    if (type == DISPATCH_TYPE_BLOCKING_NOTIFY_MAIN) {
+      eventsToAck.push_back(
+          WebInputEventTraits::GetUniqueTouchEventId(other.event));

[tdresser, 2016/06/28 14:04:49]

We're going to end up pushing a bunch of zero's in the touchpad case, aren't we?

[dtapuska, 2016/06/28 17:30:21]

It shouldn't really happen.

+    }
     BaseClass::CoalesceWith(other);
   }
 };
 
 using PendingMouseWheelEvent =
     EventWithDispatchType<MouseWheelEventWithLatencyInfo,
                           blink::WebMouseWheelEvent>;
 
 using PendingTouchEvent =
     EventWithDispatchType<TouchEventWithLatencyInfo, blink::WebTouchEvent>;
 
 class CONTENT_EXPORT MainThreadEventQueueClient {
  public:
   // Send an |event| that was previously queued (possibly
   // coalesced with another event) to the |routing_id|'s
   // channel. Implementors must implement this callback.
   virtual void SendEventToMainThread(int routing_id,
                                      const blink::WebInputEvent* event,
                                      const ui::LatencyInfo& latency,
                                      InputEventDispatchType dispatch_type) = 0;
+
+  virtual void SendInputEventAck(int routing_id,
+                                 blink::WebInputEvent::Type type,
+                                 InputEventAckState ack_result,
+                                 uint32_t touch_event_id) = 0;
 };
 
 // MainThreadEventQueue implements a series of queues (one touch
 // and one mouse wheel) for events that need to be queued between
 // the compositor and main threads. When an event is sent
 // from the compositor to main it can either be sent directly if no
 // outstanding events of that type are in flight; or it needs to
 // wait in a queue until the main thread has finished processing
 // the in-flight event. This class tracks the state and queues
 // for the event types. Methods on this class should only be called
@@ skipping 32 matching lines @@
 
   // 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(const blink::WebInputEvent* event,
                    const ui::LatencyInfo& latency,
                    InputEventDispatchType dispatch_type,
                    InputEventAckState ack_result);
 
   // Call once the main thread has handled an outstanding |type| event
   // in flight.
-  void EventHandled(blink::WebInputEvent::Type type);
+  void EventHandled(blink::WebInputEvent::Type type,
+                    InputEventAckState ack_result);
 
   void set_is_flinging(bool is_flinging) { is_flinging_ = is_flinging; }
 
  private:
   friend class MainThreadEventQueueTest;
   int routing_id_;
   MainThreadEventQueueClient* client_;
   WebInputEventQueue<PendingMouseWheelEvent> wheel_events_;
   WebInputEventQueue<PendingTouchEvent> touch_events_;
   bool is_flinging_;
 
+  // TODO(dtapuska): These can be removed when the queues are dequeued

[tdresser, 2016/06/28 14:04:49]

Can we link to a bug here?

[dtapuska, 2016/06/28 17:30:21]

Done.

+  // on the main thread.
+  std::unique_ptr<PendingMouseWheelEvent> in_flight_wheel_event_;
+  std::unique_ptr<PendingTouchEvent> in_flight_touch_event_;
+
   DISALLOW_COPY_AND_ASSIGN(MainThreadEventQueue);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_INPUT_MAIN_THREAD_EVENT_QUEUE_H_