Allow offset for secondary display position in chrome://settings/display.

ash/display/display_controller.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 ASH_DISPLAY_DISPLAY_CONTROLLER_H_
 #define ASH_DISPLAY_DISPLAY_CONTROLLER_H_
 
 #include <map>
 #include <vector>
 
@@ skipping 50 matching lines @@
 
   // Returns all oot window controllers. In non extended desktop
   // mode, this return a RootWindowController for the primary root window only.
   std::vector<internal::RootWindowController*> GetAllRootWindowControllers();
 
   SecondaryDisplayLayout secondary_display_layout() const {
     return secondary_display_layout_;
   }
   void SetSecondaryDisplayLayout(SecondaryDisplayLayout layout);
 
+  int secondary_display_offset() const {
+    return secondary_display_offset_;
+  }
+  void SetSecondaryDisplayOffset(int offset);
+
   void set_dont_warp_mouse(bool dont_warp_mouse) {
     dont_warp_mouse_ = dont_warp_mouse;
   }
 
   // Warps the mouse cursor to an alternate root window when the
   // |point_in_root|, which is the location of the mouse cursor,
   // hits or exceeds the edge of the |root_window| and the mouse cursor
   // is considered to be in an alternate display. Returns true if
   // the cursor was moved.
   bool WarpMouseCursorIfNecessary(aura::RootWindow* root_window,
@@ skipping 12 matching lines @@
   // Creates a root window for |display| and stores it in the |root_windows_|
   // map.
   aura::RootWindow* AddRootWindowForDisplay(const gfx::Display& display);
 
   void UpdateDisplayBoundsForLayout();
 
   std::map<int, aura::RootWindow*> root_windows_;
 
   SecondaryDisplayLayout secondary_display_layout_;
 
+  // The offset of the position of the secondary display.  The offset is
+  // based on the top/left edge of the primary display.
+  int secondary_display_offset_;
+
   // If true, the mouse pointer can't move from one display to another.
   bool dont_warp_mouse_;
 
   DISALLOW_COPY_AND_ASSIGN(DisplayController);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_DISPLAY_DISPLAY_CONTROLLER_H_