Use persistent ID/names for displays.

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 77 matching lines @@
   virtual void OnDisplayRemoved(const gfx::Display& display) OVERRIDE;
 
   // Is extended desktop enabled?
   static bool IsExtendedDesktopEnabled();
 
  private:
   FRIEND_TEST_ALL_PREFIXES(WorkspaceWindowResizerTest, WarpMousePointer);
 
   // Creates a root window for |display| and stores it in the |root_windows_|
   // map.
-  aura::RootWindow* AddRootWindowForDisplay(const gfx::Display& display);
+  // TODO(oshima): remove |is_primary| when non extended desktop mode is
+  // removed.
+  aura::RootWindow* AddRootWindowForDisplay(const gfx::Display& display,
+                                            bool is_primary);
 
   void UpdateDisplayBoundsForLayout();
 
-  std::map<int, aura::RootWindow*> root_windows_;
+  std::map<int64, aura::RootWindow*> root_windows_;
 
   SecondaryDisplayLayout secondary_display_layout_;
 
   // 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_