Add Vector2d classes that represent offsets, instead of using Point.

ui/views/controls/menu/menu_controller.cc

Index: ui/views/controls/menu/menu_controller.cc
diff --git a/ui/views/controls/menu/menu_controller.cc b/ui/views/controls/menu/menu_controller.cc
index 87eeca412ac7f76fe7d140fd056dcc9b6cd60084..796b45fabd7a4768b36c13a87ce303cacf754abf 100644
--- a/ui/views/controls/menu/menu_controller.cc
+++ b/ui/views/controls/menu/menu_controller.cc
@@ -450,10 +450,8 @@ void MenuController::OnMouseDragged(SubmenuView* source,
     return;
 
   if (possible_drag_) {
-    if (View::ExceededDragThreshold(event.x() - press_pt_.x(),
-                                    event.y() - press_pt_.y())) {
+    if (View::ExceededDragThreshold(event.location() - press_pt_))
       StartDrag(source, press_pt_);
-    }
     return;
   }
   MenuItemView* mouse_menu = NULL;
@@ -859,7 +857,8 @@ void MenuController::StartDrag(SubmenuView* source,
 
   OSExchangeData data;
   item->GetDelegate()->WriteDragData(item, &data);
-  drag_utils::SetDragImageOnDataObject(*canvas, item->size(), press_loc,
+  drag_utils::SetDragImageOnDataObject(*canvas, item->size(),
+                                       press_loc.OffsetFromOrigin(),
                                        &data);
   StopScrolling();
   int drag_ops = item->GetDelegate()->GetDragOperations(item);