Coalesce async touch move events until the ack back from render

content/browser/renderer_host/input/touch_event_queue.cc

Index: content/browser/renderer_host/input/touch_event_queue.cc
diff --git a/content/browser/renderer_host/input/touch_event_queue.cc b/content/browser/renderer_host/input/touch_event_queue.cc
index b766b3d1b51530ec4b49d9685cde78ebb302b525..469745fe774c10eba5ab4ac5ec75016988d2dc6e 100644
--- a/content/browser/renderer_host/input/touch_event_queue.cc
+++ b/content/browser/renderer_host/input/touch_event_queue.cc
@@ -372,6 +372,9 @@ TouchEventQueue::TouchEventQueue(TouchEventQueueClient* client,
       drop_remaining_touches_in_sequence_(false),
       touchmove_slop_suppressor_(new TouchMoveSlopSuppressor),
       send_touch_events_async_(false),
+      receive_async_touch_move_ack_(false),
+      ignore_ack_(0),
+      sent_async_touch_move_count_(0),
       last_sent_touch_timestamp_sec_(0) {
   DCHECK(client);
   if (config.touch_ack_timeout_supported) {
@@ -430,7 +433,6 @@ void TouchEventQueue::ProcessTouchAck(InputEventAckState ack_result,
     return;
 
   touchmove_slop_suppressor_->ConfirmTouchEvent(ack_result);
-
   if (touch_queue_.empty())
     return;
 
@@ -438,6 +440,23 @@ void TouchEventQueue::ProcessTouchAck(InputEventAckState ack_result,
   TryForwardNextEventToRenderer();
 }
 
+void TouchEventQueue::ProcessAsyncTouchAck() {
+  TRACE_EVENT0("input", "TouchEventQueue::ProcessAsyncTouchAck");
+
+  DCHECK(!dispatching_touch_ack_);
+  dispatching_touch_ = false;
+  --sent_async_touch_move_count_;
+  if (ignore_ack_ > 0)
+    --ignore_ack_;
+  receive_async_touch_move_ack_ = true;
+
+  if (pending_async_touchmove_) {
+    touch_queue_.push_front(
+        new CoalescedWebTouchEvent(*pending_async_touchmove_, true));
+    SendTouchEventImmediately(pending_async_touchmove_.get());
+  }
+}
+
 void TouchEventQueue::TryForwardNextEventToRenderer() {
   DCHECK(!dispatching_touch_ack_);
   // If there are queued touch events, then try to forward them to the renderer
@@ -480,6 +499,8 @@ void TouchEventQueue::ForwardNextEventToRenderer() {
         touch.event.timeStampSeconds >=
         last_sent_touch_timestamp_sec_ + kAsyncTouchMoveIntervalSec;
 
+    if (ignore_ack_ == 0)
+      send_touchmove_now &= receive_async_touch_move_ack_;
     if (!send_touchmove_now) {
       if (!pending_async_touchmove_) {
         pending_async_touchmove_.reset(new TouchEventWithLatencyInfo(touch));
@@ -496,6 +517,7 @@ void TouchEventQueue::ForwardNextEventToRenderer() {
       TryForwardNextEventToRenderer();
       return;
     }
+    receive_async_touch_move_ack_ = false;
   }
 
   last_sent_touch_timestamp_sec_ = touch.event.timeStampSeconds;
@@ -509,7 +531,12 @@ void TouchEventQueue::ForwardNextEventToRenderer() {
       pending_async_touchmove_->event.cancelable = !send_touch_events_async_;
       touch = *pending_async_touchmove_;
       pending_async_touchmove_.reset();
+      if (!touch.event.cancelable)
+        ++sent_async_touch_move_count_;
     } else {
+      // Once we flish the pending async touch move, we ignore all the acks

[tdresser, 2015/03/23 19:21:44]

flish -> flush

[lanwei, 2015/03/24 18:46:38]

Done.

+      // from the aysnc touch moves that we sent out and wait for acks back.

[tdresser, 2015/03/23 19:21:44]

Fix aysnc spelling.

[lanwei, 2015/03/24 18:46:38]

Done.

+      ignore_ack_ = ++sent_async_touch_move_count_;

[tdresser, 2015/03/23 19:21:44]

Split into two statements.

[lanwei, 2015/03/24 18:46:38]

Done.

       scoped_ptr<TouchEventWithLatencyInfo> async_move =
           pending_async_touchmove_.Pass();
       async_move->event.cancelable = false;