Move supports-high-dpi flag into registry.

ui/gfx/win/dpi.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_GFX_DPI_WIN_H_
 #define UI_GFX_DPI_WIN_H_
 
 #include "ui/gfx/gfx_export.h"
 #include "ui/gfx/point.h"
 #include "ui/gfx/rect.h"
@@ skipping 19 matching lines @@
 // unscaled or "not running on win8+"
 GFX_EXPORT float GetModernUIScale();
 
 // Tests to see if the command line flag "--high-dpi-support" is set.
 GFX_EXPORT bool IsHighDPIEnabled();
 
 GFX_EXPORT bool IsInHighDPIMode();
 
 GFX_EXPORT void EnableHighDPISupport();
 
+GFX_EXPORT void ForceHighDPISupportForTesting(float scale);
+
 // TODO(kevers|girard):  Move above methods into win namespace.
 
 namespace win {
 
 GFX_EXPORT float GetDeviceScaleFactor();
 
 GFX_EXPORT Point ScreenToDIPPoint(const Point& pixel_point);
 
 GFX_EXPORT Point DIPToScreenPoint(const Point& dip_point);
 
@@ skipping 19 matching lines @@
 
 // Win7 and Win8 send touch events scaled according to the current DPI
 // scaling. Win8.1 corrects this, and sends touch events in DPI units.
 // This function returns the appropriate scaling factor for touch events.
 GFX_EXPORT double GetUndocumentedDPITouchScale();
 
 }  // namespace win
 }  // namespace gfx
 
 #endif  // UI_GFX_DPI_WIN_H_