Context menus should appear above the touch point if invoked by long press.

ui/views/controls/menu/menu_item_view.h

 // Copyright (c) 2012 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.
 
 #ifndef UI_VIEWS_CONTROLS_MENU_MENU_ITEM_VIEW_H_
 #define UI_VIEWS_CONTROLS_MENU_MENU_ITEM_VIEW_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 73 matching lines @@
     CHECKBOX,
     RADIO,
     SEPARATOR,
     EMPTY
   };
 
   // Where the menu should be anchored to for non-RTL languages.  The
   // opposite position will be used if base::i18n:IsRTL() is true.
   enum AnchorPosition {
     TOPLEFT,
-    TOPRIGHT
+    TOPRIGHT,
+    BOTTOMCENTER
   };
 
   // Where the menu should be drawn, above or below the bounds (when
   // the bounds is non-empty).  POSITION_BEST_FIT (default) positions
   // the menu below the bounds unless the menu does not fit on the
   // screen and the re is more space above.
   enum MenuPosition {
     POSITION_BEST_FIT,
     POSITION_ABOVE_BOUNDS,
     POSITION_BELOW_BOUNDS
@@ skipping 393 matching lines @@
   // If set to false, the right margin will be removed for menu lines
   // containing other elements.
   bool use_right_margin_;
 
   DISALLOW_COPY_AND_ASSIGN(MenuItemView);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_MENU_MENU_ITEM_VIEW_H_