Fix font sizes being incorrect when using --force-device-scale-factor.

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 84 matching lines @@
   static int GetSystemMetricsForHwnd(HWND hwnd, int metric);
 
   // Returns the result of GetSystemMetrics for |metric| in DIP.
   // Use this function if you need to work in DIP and can tolerate cascading
   // rounding errors towards screen pixels.
   static int GetSystemMetricsInDIP(int metric);
 
   // Returns |hwnd|'s scale factor.
   static float GetScaleFactorForHWND(HWND hwnd);
 
+  // Returns the system's global scale factor, ignoring the value of
+  // --force-device-scale-factor. Only use this if you are working with Windows
+  // metrics global to the system. Otherwise you should call
+  // GetScaleFactorForHWND() to get the correct scale factor for the monitor
+  // you are on.

[robliao, 2017/02/15 22:59:41]

Nit: correct scale factor for the target monitor.
Ending sentences with a preposition :-D.

[Bret, 2017/02/15 23:13:46]

Okay, Bishop Lowth. I edited it anyway since target is more generic than what
monitor you're drawing to.

+  static float GetSystemScaleFactor();
+
   // Returns the HWND associated with the NativeView.
   virtual HWND GetHWNDFromNativeView(gfx::NativeView window) const;
 
   // Returns the NativeView associated with the HWND.
   virtual gfx::NativeWindow GetNativeWindowFromHWND(HWND hwnd) const;
 
  protected:
   // Screen:
   gfx::Point GetCursorScreenPoint() override;
   bool IsWindowUnderCursor(gfx::NativeWindow window) override;
@@ skipping 71 matching lines @@
   // This must be updated anytime |screen_win_displays_| is updated.
   std::vector<Display> displays_;
 
   DISALLOW_COPY_AND_ASSIGN(ScreenWin);
 };
 
 }  // namespace win
 }  // namespace display
 
 #endif  // UI_DISPLAY_WIN_SCREEN_WIN_H_