Pass location with gestures created in TouchDispositionGestureFilter

ui/events/gesture_detection/touch_disposition_gesture_filter.cc

Index: ui/events/gesture_detection/touch_disposition_gesture_filter.cc
diff --git a/ui/events/gesture_detection/touch_disposition_gesture_filter.cc b/ui/events/gesture_detection/touch_disposition_gesture_filter.cc
index bfff7809b16651a3f5d3b7a912416d1132e51ae4..1dd73603d010c47a3f02ad9ea679915d999fdae0 100644
--- a/ui/events/gesture_detection/touch_disposition_gesture_filter.cc
+++ b/ui/events/gesture_detection/touch_disposition_gesture_filter.cc
@@ -17,15 +17,17 @@ COMPILE_ASSERT(ET_GESTURE_TYPE_END - ET_GESTURE_TYPE_START < 32,
 
 GestureEventData CreateGesture(EventType type,
                                int motion_event_id,
-                               const base::TimeTicks& timestamp) {
+                               const base::TimeTicks& timestamp,
+                               float x,
+                               float y) {
   GestureEventDetails details(type, 0, 0);
   return GestureEventData(type,
                           motion_event_id,
                           timestamp,
-                          0,
-                          0,
+                          x,
+                          y,
                           1,
-                          gfx::RectF(0, 0, 0, 0),
+                          gfx::RectF(x, y, 0, 0),
                           details);
 }
 
@@ -205,6 +207,8 @@ bool TouchDispositionGestureFilter::IsEmpty() const {
 
 void TouchDispositionGestureFilter::FilterAndSendPacket(
     const GestureEventDataPacket& packet) {
+  ending_event_location_ = packet.touch_location();

[jdduke (slow), 2014/05/12 17:02:34]

It appears we only call |{Cancel,End}FooIfNecessary()| within the context of a
|FilterAndSendPacket()|.  

I wonder if it would be simpler if we made this explicit, in which case we'd
have a GestureEventDataPacket* |packet_being_sent_| or |current_packet_| member
variable that we |base::AutoReset| here.  Then we can just pull the timestamp
and location directly in the cancel/end functions, asserting that
|packet_being_sent_| is non-null and ripping out the timestamp that we pass
around everywhere. What do you think?

If we do that, it's probably worth adding a DCHECK(!packet_being_sent_) in the
destructor.

[tdresser, 2014/05/12 18:09:31]

SGTM.
Done.

+
   if (packet.gesture_source() == GestureEventDataPacket::TOUCH_SEQUENCE_START) {
     CancelTapIfNecessary(packet.timestamp());
     EndScrollIfNecessary(packet.timestamp());
@@ -300,8 +304,11 @@ void TouchDispositionGestureFilter::CancelTapIfNecessary(
   if (!needs_tap_ending_event_)
     return;
 
-  SendGesture(CreateGesture(
-      ET_GESTURE_TAP_CANCEL, ending_event_motion_event_id_, timestamp));
+  SendGesture(CreateGesture(ET_GESTURE_TAP_CANCEL,
+                            ending_event_motion_event_id_,
+                            timestamp,
+                            ending_event_location_.x(),
+                            ending_event_location_.y()));
   DCHECK(!needs_tap_ending_event_);
 }
 
@@ -310,8 +317,11 @@ void TouchDispositionGestureFilter::CancelFlingIfNecessary(
   if (!needs_fling_ending_event_)
     return;
 
-  SendGesture(CreateGesture(
-      ET_SCROLL_FLING_CANCEL, ending_event_motion_event_id_, timestamp));
+  SendGesture(CreateGesture(ET_SCROLL_FLING_CANCEL,
+                            ending_event_motion_event_id_,
+                            timestamp,
+                            ending_event_location_.x(),
+                            ending_event_location_.y()));
   DCHECK(!needs_fling_ending_event_);
 }
 
@@ -320,8 +330,11 @@ void TouchDispositionGestureFilter::EndScrollIfNecessary(
   if (!needs_scroll_ending_event_)
     return;
 
-  SendGesture(CreateGesture(
-      ET_GESTURE_SCROLL_END, ending_event_motion_event_id_, timestamp));
+  SendGesture(CreateGesture(ET_GESTURE_SCROLL_END,
+                            ending_event_motion_event_id_,
+                            timestamp,
+                            ending_event_location_.x(),
+                            ending_event_location_.y()));
   DCHECK(!needs_scroll_ending_event_);
 }