Ensure acks are sent for all blocking events.

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 6a99636a9a0d2f0851d7404b89778eb676a733a8..4a36b1551df81f65f9be49ab8f5a30566f14e644 100644
--- a/content/renderer/input/main_thread_event_queue.h
+++ b/content/renderer/input/main_thread_event_queue.h
@@ -25,6 +25,7 @@ class EventWithDispatchType : public BaseClass {
       : 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 {
@@ -32,6 +33,12 @@ class EventWithDispatchType : public BaseClass {
   }
 
   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);
   }
 };
@@ -52,6 +59,11 @@ class CONTENT_EXPORT MainThreadEventQueueClient {
                                      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
@@ -104,7 +116,8 @@ class CONTENT_EXPORT MainThreadEventQueue {
 
   // 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; }
 
@@ -116,6 +129,11 @@ class CONTENT_EXPORT MainThreadEventQueue {
   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);
 };