Aura: Support hovering restore & close buttons for full screen apps

ui/views/window/non_client_view.cc

Index: ui/views/window/non_client_view.cc
diff --git a/ui/views/window/non_client_view.cc b/ui/views/window/non_client_view.cc
index c880414ef2e6278b1763005b3518a8ede724aa37..b6def60cc9332fd437ceb7c232b07f3fd99ee20a 100644
--- a/ui/views/window/non_client_view.cc
+++ b/ui/views/window/non_client_view.cc
@@ -168,10 +168,15 @@ views::View* NonClientView::GetEventHandlerForPoint(const gfx::Point& point) {
   // detect this condition and re-route the events to the non-client frame view.
   // The assumption is that the frame view's implementation of HitTest will only
   // return true for area not occupied by the client view.
-  gfx::Point point_in_child_coords(point);
-  View::ConvertPointToView(this, frame_view_.get(), &point_in_child_coords);
-  if (frame_view_->HitTest(point_in_child_coords))
-    return frame_view_->GetEventHandlerForPoint(point_in_child_coords);
+  if (frame_view_->parent() == this) {
+    // During the reset of the frame_view_ it's possible to be in this code
+    // after it's been removed from the view hierarchy but before it's been
+    // removed from the NonClientView.
+    gfx::Point point_in_child_coords(point);
+    View::ConvertPointToView(this, frame_view_.get(), &point_in_child_coords);
+    if (frame_view_->HitTest(point_in_child_coords))
+      return frame_view_->GetEventHandlerForPoint(point_in_child_coords);
+  }
 
   return View::GetEventHandlerForPoint(point);
 }