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

ash/screen_ash.h

Index: ash/screen_ash.h
diff --git a/ash/screen_ash.h b/ash/screen_ash.h
index ea2021f68519babe2aefb5820ec91804b26b41e2..33e6fc95d65e3644682a6a40eecac109fb83ab0b 100644
--- a/ash/screen_ash.h
+++ b/ash/screen_ash.h
@@ -19,7 +19,7 @@ namespace ash {
 
 // Aura implementation of gfx::Screen. Implemented here to avoid circular
 // dependencies.
-class ASH_EXPORT ScreenAsh : public gfx::Screen {
+class ASH_EXPORT ScreenAsh : public gfx::ScreenImpl {
  public:
   explicit ScreenAsh(aura::RootWindow* root_window);
   virtual ~ScreenAsh();
@@ -32,18 +32,18 @@ class ASH_EXPORT ScreenAsh : public gfx::Screen {
   static gfx::Rect GetUnmaximizedWorkAreaBounds(aura::Window* window);
 
  protected:
-  virtual gfx::Point GetCursorScreenPointImpl() OVERRIDE;
-  virtual gfx::Rect GetMonitorWorkAreaNearestWindowImpl(
-      gfx::NativeView view) OVERRIDE;
-  virtual gfx::Rect GetMonitorAreaNearestWindowImpl(
+  virtual gfx::Point GetCursorScreenPoint() OVERRIDE;
+  virtual gfx::NativeWindow GetWindowAtCursorScreenPoint() OVERRIDE;
+
+  virtual int GetNumMonitors() OVERRIDE;
+  virtual const gfx::Monitor* GetMonitorNearestWindow(
       gfx::NativeView view) OVERRIDE;
-  virtual gfx::Rect GetMonitorWorkAreaNearestPointImpl(
+  virtual const gfx::Monitor* GetMonitorNearestPoint(
       const gfx::Point& point) OVERRIDE;
-  virtual gfx::Rect GetMonitorAreaNearestPointImpl(
-      const gfx::Point& point) OVERRIDE;
-  virtual gfx::NativeWindow GetWindowAtCursorScreenPointImpl() OVERRIDE;
-  virtual gfx::Size GetPrimaryMonitorSizeImpl() OVERRIDE;
-  virtual int GetNumMonitorsImpl() OVERRIDE;
+  virtual const gfx::Monitor* GetPrimaryMonitor() OVERRIDE;
+
+  virtual void AddMonitorObserver(gfx::MonitorObserver* observer) OVERRIDE;
+  virtual void RemoveMonitorObserver(gfx::MonitorObserver* observer) OVERRIDE;
 
  private:
   aura::RootWindow* root_window_;