Refactor screen/monitor so that gfx::Screen returns monitor object.

ui/aura/monitor_aura.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_AURA_MONITOR_H_
 #define UI_AURA_MONITOR_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "ui/aura/aura_export.h"
 #include "ui/gfx/insets.h"
+#include "ui/gfx/monitor.h"
 #include "ui/gfx/rect.h"
 
 namespace aura {
 
-class AURA_EXPORT Monitor {
+class AURA_EXPORT MonitorAura : public gfx::Monitor {
  public:
-  Monitor();
-  ~Monitor();
+  MonitorAura();
+  virtual ~MonitorAura();
 
   // Sets/gets monitor's bounds in |gfx::screen|'s coordinates,
   // which is relative to the primary screen's origin.
   void set_bounds(const gfx::Rect& bounds) { bounds_ = bounds;}
   const gfx::Rect& bounds() const { return bounds_; };
 
   // Sets/gets monitor's size.
   void set_size(const gfx::Size& size) { bounds_.set_size(size); }
   const gfx::Size& size() const { return bounds_.size(); }
 
   // Sets/gets monitor's workarea insets.
   void set_work_area_insets(const gfx::Insets& insets) {
     work_area_insets_ = insets;
   }
   const gfx::Insets& work_area_insets() const { return work_area_insets_; }
 
-  // Returns the monitor's work area.
-  gfx::Rect GetWorkAreaBounds() const;
+  // Sets the device scale factor.
+  void set_device_scale_factor(float scale) {
+    device_scale_factor_ = scale;
+  }
+
+  // gfx::Monitor overrides:
+  virtual gfx::Rect GetBounds() const OVERRIDE;
+  virtual gfx::Rect GetWorkArea() const OVERRIDE;
+  virtual float GetDeviceScaleFactor() const OVERRIDE;
 
  private:
   // Insets for the work area.
   gfx::Insets work_area_insets_;
 
   gfx::Rect bounds_;
 
-  DISALLOW_COPY_AND_ASSIGN(Monitor);
+  float device_scale_factor_;
+
+  DISALLOW_COPY_AND_ASSIGN(MonitorAura);
 };
 
-}  // namespace aura
+}  // namespace gfx
 
-#endif  // UI_AURA_MONITOR_H_
+#endif  // UI_GFX_MONITOR_H_