Re-enable Eager Gesture Recognition on Aura

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index a7eb8d667baec6cc472c40178036fbbd5c092b27..ac10eafaa0707086c13293f7bff616668872473a 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -1163,7 +1163,7 @@ void RenderWidgetHostViewAura::ProcessAckedTouchEvent(
     return;
 
   aura::WindowTreeHost* host = window_->GetHost();
-  // |host| is NULL during tests.
+  // |host| may be null during tests.
   if (!host)
     return;
 
@@ -2028,8 +2028,10 @@ void RenderWidgetHostViewAura::OnTouchEvent(ui::TouchEvent* event) {
     return;
 
   // Update the touch event first.
-  blink::WebTouchPoint* point = UpdateWebTouchEventFromUIEvent(*event,
-                                                                &touch_event_);
+  blink::WebTouchPoint* point =
+      UpdateWebTouchEventFromUIEvent(*event, &touch_event_);
+
+  bool should_forward = host_->ShouldForwardTouchEvent();
 
   // Forward the touch event only if a touch point was updated, and there's a
   // touch-event handler in the page, and no other touch-event is in the queue.
@@ -2037,14 +2039,17 @@ void RenderWidgetHostViewAura::OnTouchEvent(ui::TouchEvent* event) {
   // handler in the page, or some touch-event is already in the queue, even if
   // no point has been updated, to make sure that this event does not get
   // processed by the gesture recognizer before the events in the queue.
-  if (host_->ShouldForwardTouchEvent())
+  if (point && should_forward) {
+    DCHECK(window_->GetHost());
+    if (window_->GetHost()->dispatcher()->OnForwardingAsyncTouchEvent(event))
+      host_->ForwardTouchEventWithLatencyInfo(touch_event_, *event->latency());
+  }
+
+  if (should_forward)
     event->StopPropagation();

[jdduke (slow), 2014/10/22 17:51:02]

Does it matter that the touch may have been ack'ed synchronously even if it was
forwarded? Will calling StopPropagation do the right thing in that case?

[tdresser, 2014/10/22 18:24:08]

In that case, we'll synchronously hit
WindowEventDispatcher::ProcessedTouchEvent, and turn the touch into a gesture
(if necessary), before the StopPropagation call occurs. 

I think its fine.

 
-  if (point) {
-    if (host_->ShouldForwardTouchEvent())
-      host_->ForwardTouchEventWithLatencyInfo(touch_event_, *event->latency());
+  if (point)
     UpdateWebTouchEventAfterDispatch(&touch_event_, point);
-  }
 }
 
 void RenderWidgetHostViewAura::OnGestureEvent(ui::GestureEvent* event) {