Pass the device scale factor in the command line to renderer processes.

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 51 matching lines @@
 // Returns the scale factor of the display, where 96 DPI is 1.0.
 // (Avoid this function... use GetDPIScale() instead.)
 // TODO(girard): Remove this once DPIAware is enabled - http://crbug.com/149881
 GFX_EXPORT double GetUndocumentedDPIScale();
 
 // 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();
 
+// Returns true if the global device scale factor has been explicitly set for
+// the process.
+GFX_EXPORT bool IsDeviceScaleFactorSet();
+
 }  // namespace win
 }  // namespace gfx
 
 #endif  // UI_GFX_DPI_WIN_H_