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

ui/gfx/win/dpi.cc

 // 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.
 
 #include "ui/gfx/win/dpi.h"
 
 #include <windows.h>
 #include "base/command_line.h"
 #include "base/win/scoped_hdc.h"
 #include "base/win/windows_version.h"
@@ skipping 154 matching lines @@
 void EnableHighDPISupport() {
   if (IsHighDPIEnabled() &&
       !SetProcessDpiAwarenessWrapper(PROCESS_SYSTEM_DPI_AWARE)) {
     SetProcessDPIAwareWrapper();
   }
 }
 
 namespace win {
 
 float GetDeviceScaleFactor() {
-  DCHECK_NE(0.0f, g_device_scale_factor);

[ananta, 2014/06/03 01:04:02]

Removed this DCHECK as we need to call this to see if it has been set which
causes the DCHECK to fire. Not needed as this was added as a precaution early
in the high dpi work for Windows.

   return g_device_scale_factor;
 }
 
 Point ScreenToDIPPoint(const Point& pixel_point) {
   return ToFlooredPoint(ScalePoint(pixel_point,
       1.0f / GetDeviceScaleFactor()));
 }
 
 Point DIPToScreenPoint(const Point& dip_point) {
   return ToFlooredPoint(ScalePoint(dip_point, GetDeviceScaleFactor()));
@@ skipping 55 matching lines @@
 
 double GetUndocumentedDPITouchScale() {
   static double scale =
       (base::win::GetVersion() < base::win::VERSION_WIN8_1) ?
       GetUndocumentedDPIScale() : 1.0;
   return scale;
 }
 
 }  // namespace win
 }  // namespace gfx