Re-enable Eager Gesture Recognition on Aura

ui/aura/window_event_dispatcher.cc

Index: ui/aura/window_event_dispatcher.cc
diff --git a/ui/aura/window_event_dispatcher.cc b/ui/aura/window_event_dispatcher.cc
index eadda03f6794645960382900eb4dcc4970ebb0a6..10afe1bea0c7963549d35ba45f3afd22400a13ac 100644
--- a/ui/aura/window_event_dispatcher.cc
+++ b/ui/aura/window_event_dispatcher.cc
@@ -159,17 +159,10 @@ DispatchDetails WindowEventDispatcher::DispatchMouseExitAtPoint(
 void WindowEventDispatcher::ProcessedTouchEvent(ui::TouchEvent* event,
                                                 Window* window,
                                                 ui::EventResult result) {
-  // TODO(tdresser): Move this to PreDispatchTouchEvent, to enable eager
-  // gesture detection. See crbug.com/410280.
-  if (!ui::GestureRecognizer::Get()
-           ->ProcessTouchEventPreDispatch(*event, window)) {
-    return;
-  }
-
   // Once we've fully migrated to the eager gesture detector, we won't need to
   // pass an event here.

[sadrul, 2014/12/03 21:30:10]

Is this comment still correct?

[tdresser, 2014/12/05 16:44:31]

I'm performing that cleanup in a followup patch:
https://codereview.chromium.org/503883004/

Note that we're only using the touch event unique identifier to double check
that we're acking the right event for the synchronous case.

   scoped_ptr<ui::GestureRecognizer::Gestures> gestures(
-      ui::GestureRecognizer::Get()->ProcessTouchEventOnAsyncAck(
+      ui::GestureRecognizer::Get()->AckAsyncTouchEvent(
           *event, result, window));
   DispatchDetails details = ProcessGestures(gestures.get());
   if (details.dispatcher_destroyed)
@@ -499,30 +492,18 @@ ui::EventDispatchDetails WindowEventDispatcher::PostDispatchEvent(
     if (dispatching_held_event_ || !held_move_event_ ||
         !held_move_event_->IsTouchEvent()) {
 
-      // Once we've fully migrated to the eager gesture detector, we won't
-      // need to pass an event here.
-      ui::TouchEvent orig_event(static_cast<const ui::TouchEvent&>(event),
-                                static_cast<Window*>(event.target()),
-                                window());
+      if (!event.synchronous_handling_disabled()) {
+        scoped_ptr<ui::GestureRecognizer::Gestures> gestures;
 
-      if (event.result() & ui::ER_CONSUMED)
-        orig_event.StopPropagation();
+        // Once we've fully migrated to the eager gesture detector, we won't
+        // need to pass an event here.
+        gestures.reset(
+            ui::GestureRecognizer::Get()->AckSyncTouchEvent(
+                static_cast<const ui::TouchEvent&>(event), event.result(),
+                static_cast<Window*>(target)));

[sadrul, 2014/12/03 21:30:10]

This touch-event is being sent in the target's coord space. I believe the rest
of the touch-events are sent in the root-window's coord space. Is this not
problematic?

[tdresser, 2014/12/05 16:44:31]

It isn't problematic because we're only using the touch event's unique_event_id.

I've clarified that we're only using the unique_event_id by only passing the id
- I think strongly typing the id is probably worth it here, though it is a
little ugly.

 
-      // TODO(tdresser): Move this to PreDispatchTouchEvent, to enable eager
-      // gesture detection. See crbug.com/410280.
-      if (!ui::GestureRecognizer::Get()
-               ->ProcessTouchEventPreDispatch(orig_event,
-                                              static_cast<Window*>(target))) {
-        return details;
+        return ProcessGestures(gestures.get());
       }
-
-      scoped_ptr<ui::GestureRecognizer::Gestures> gestures;
-
-      gestures.reset(
-          ui::GestureRecognizer::Get()->ProcessTouchEventPostDispatch(
-              orig_event, event.result(), static_cast<Window*>(target)));
-
-      return ProcessGestures(gestures.get());
     }
   }
 
@@ -901,6 +882,15 @@ void WindowEventDispatcher::PreDispatchTouchEvent(Window* target,
       break;
   }
 
+  ui::TouchEvent orig_event(*event, target, window());
+  if (!ui::GestureRecognizer::Get()->ProcessTouchEventPreDispatch(orig_event,
+                                                                  target)) {
+    // The event is invalid - ignore it.
+    event->StopPropagation();
+    event->DisableSynchronousHandling();
+    return;
+  }
+
   PreDispatchLocatedEvent(target, event);
 }