Only target ui::ET_GESTURE_END to the default gesture handler

ui/views/widget/root_view_targeter.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/views/widget/root_view_targeter.h"
 
 #include "ui/views/view.h"
 #include "ui/views/view_targeter_delegate.h"
 #include "ui/views/views_switches.h"
 #include "ui/views/widget/root_view.h"
@@ skipping 13 matching lines @@
     View* root,
     const ui::GestureEvent& gesture) {
   CHECK_EQ(root, root_view_);
 
   // Return the default gesture handler if one is already set.
   if (root_view_->gesture_handler_) {
     CHECK(!root_view_->allow_gesture_event_retargeting_);
     return root_view_->gesture_handler_;
   }
 
+  // If no default gesture handler has already been set, do not perform any
+  // targeting for a ET_GESTURE_END event.
+  if (gesture.type() == ui::ET_GESTURE_END)
+    return NULL;
+
   // If rect-based targeting is enabled, use the gesture's bounding box to
   // determine the target. Otherwise use the center point of the gesture's
   // bounding box to determine the target.
   gfx::Rect rect(gesture.location(), gfx::Size(1, 1));
   if (views::switches::IsRectBasedTargetingEnabled() &&
       !gesture.details().bounding_box().IsEmpty()) {
     // TODO(tdanderson): Pass in the bounding box to GetEventHandlerForRect()
     // once crbug.com/313392 is resolved.
     rect.set_size(gesture.details().bounding_box().size());
     rect.Offset(-rect.width() / 2, -rect.height() / 2);
   }
 
   return root->GetEffectiveViewTargeter()->TargetForRect(root, rect);
 }
 
 ui::EventTarget* RootViewTargeter::FindNextBestTargetForGestureEvent(
     ui::EventTarget* previous_target,
     const ui::GestureEvent& gesture) {
+  // ET_GESTURE_END events should only ever be targeted to the default
+  // gesture handler set by a previous gesture, if one exists. Thus we do not
+  // permit any re-targeting of ET_GESTURE_END events.
+  if (gesture.type() == ui::ET_GESTURE_END)
+    return NULL;
+
   // GESTURE_SCROLL_BEGIN events are always permitted to be re-targeted, even
   // if |allow_gesture_event_retargeting_| is false.
   if (!root_view_->allow_gesture_event_retargeting_ &&
       gesture.type() != ui::ET_GESTURE_SCROLL_BEGIN) {
     return NULL;
   }
 
   // If |gesture_handler_| is NULL, it is either because the view was removed
   // from the tree by the previous dispatch of |gesture| or because |gesture| is
   // the GESTURE_END event corresponding to the removal of the last touch
   // point. In either case, no further re-targeting of |gesture| should be
   // permitted.
   if (!root_view_->gesture_handler_)
     return NULL;
 
   return previous_target->GetParentTarget();
 }
 
 }  // namespace views