Move DisplayManager and DisplayChangeObserverX11 from aura to ash.

ui/gfx/screen_mac.mm

 // 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.
 
 #include "ui/gfx/screen.h"
 
 #import <ApplicationServices/ApplicationServices.h>
 #import <Cocoa/Cocoa.h>
 
 #include "base/logging.h"
@@ skipping 150 matching lines @@
 
   // Returns the primary display.
   virtual gfx::Display GetPrimaryDisplay() const OVERRIDE {
     // Primary display is defined as the display with the menubar,
     // which is always at index 0.
     NSScreen* primary = [[NSScreen screens] objectAtIndex:0];
     gfx::Display display = GetDisplayForScreen(primary, true /* primary */);
     return display;
   }
 
+  virtual void AddObserver(gfx::DisplayObserver* observer) OVERRIDE {
+    // TODO(oshima): crbug.com/122863.
+  }
+
+  virtual void RemoveObserver(gfx::DisplayObserver* observer) OVERRIDE {
+    // TODO(oshima): crbug.com/122863.
+  }
+
  private:
   DISALLOW_COPY_AND_ASSIGN(ScreenMac);
 };
 
 }  // namespace
 
 namespace gfx {
 
 Screen* CreateNativeScreen() {
   return new ScreenMac;
 }
 
 }