Use actual value of display scale factor from GetMonitorScaleFactor().

ui/display/win/screen_win.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_DISPLAY_WIN_SCREEN_WIN_H_
 #define UI_DISPLAY_WIN_SCREEN_WIN_H_
 
 #include <windows.h>
 
 #include <memory>
@@ skipping 110 matching lines @@
       const gfx::Point& point) const override;
   display::Display GetDisplayMatching(
       const gfx::Rect& match_rect) const override;
   display::Display GetPrimaryDisplay() const override;
   void AddObserver(display::DisplayObserver* observer) override;
   void RemoveObserver(display::DisplayObserver* observer) override;
   gfx::Rect ScreenToDIPRectInWindow(
       gfx::NativeView view, const gfx::Rect& screen_rect) const override;
   gfx::Rect DIPToScreenRectInWindow(
       gfx::NativeView view, const gfx::Rect& dip_rect) const override;
+  float GetScaleFactorForWindow(gfx::NativeView view) const override;
 
   void UpdateFromDisplayInfos(const std::vector<DisplayInfo>& display_infos);
 
   // Virtual to support mocking by unit tests.
   virtual void Initialize();
   virtual MONITORINFOEX MonitorInfoFromScreenPoint(
       const gfx::Point& screen_point) const;
   virtual MONITORINFOEX MonitorInfoFromScreenRect(const gfx::Rect& screen_rect)
       const;
   virtual MONITORINFOEX MonitorInfoFromWindow(HWND hwnd, DWORD default_options)
@@ skipping 44 matching lines @@
   // Current list of ScreenWinDisplays.
   std::vector<ScreenWinDisplay> screen_win_displays_;
 
   DISALLOW_COPY_AND_ASSIGN(ScreenWin);
 };
 
 }  // namespace win
 }  // namespace display
 
 #endif  // UI_DISPLAY_WIN_SCREEN_WIN_H_