Fix crash which occurs when a widget destroys itself as a result of ET_GESTURE_TAP_DOWN

ui/views/widget/root_view.cc

Index: ui/views/widget/root_view.cc
diff --git a/ui/views/widget/root_view.cc b/ui/views/widget/root_view.cc
index f3ad2a08d6849b779e7bf5634218b57b6144176f..ebab579bf139481c062ecb5963362828fe32c541 100644
--- a/ui/views/widget/root_view.cc
+++ b/ui/views/widget/root_view.cc
@@ -224,7 +224,13 @@ void RootView::DispatchGestureEvent(ui::GestureEvent* event) {
         (event->IsScrollGestureEvent() || event->IsFlingScrollEvent())  ?
             scroll_gesture_handler_ : gesture_handler_;
     ui::GestureEvent handler_event(*event, static_cast<View*>(this), handler);
-    DispatchEventToTarget(handler, &handler_event);
+
+    {
+      WidgetDeletionObserver widget_deletion_observer(widget_);
+      DispatchEventToTarget(handler, &handler_event);

[sadrul, 2014/02/18 12:53:26]

This is also an issue for other kinds of event dispatch, right?

The better fix would be to have DispatchEventToTarget return the
EventDispatchDetails, and look at dispatcher_destroyed

+      if (!widget_deletion_observer.IsWidgetAlive())
+        return;
+    }
 
     if (event->type() == ui::ET_GESTURE_END &&
         event->details().touch_points() <= 1) {
@@ -312,7 +318,13 @@ void RootView::DispatchGestureEvent(ui::GestureEvent* event) {
     // See if this view wants to handle the Gesture.
     ui::GestureEvent gesture_event(*event, static_cast<View*>(this),
                                    gesture_handler_);
-    DispatchEventToTarget(gesture_handler_, &gesture_event);
+
+    {
+      WidgetDeletionObserver widget_deletion_observer(widget_);
+      DispatchEventToTarget(gesture_handler_, &gesture_event);
+      if (!widget_deletion_observer.IsWidgetAlive())
+        return;
+    }
 
     // The view could have removed itself from the tree when handling
     // OnGestureEvent(). So handle as per OnMousePressed. NB: we