Prepare ScreenWin To Use Per-Monitor DPI

ui/display/win/dpi.cc

Index: ui/display/win/dpi.cc
diff --git a/ui/display/win/dpi.cc b/ui/display/win/dpi.cc
index 4e8f43c6b3003bc21eac493cd4c5402fe3df9953..778d83b0d468dc2cd082e98831514f6fe6b3ddb1 100644
--- a/ui/display/win/dpi.cc
+++ b/ui/display/win/dpi.cc
@@ -38,7 +38,7 @@ gfx::Size GetDPI() {
 float GetUnforcedDeviceScaleFactor() {
   return g_device_scale_factor
       ? g_device_scale_factor
-      : static_cast<float>(GetDPI().width()) / kDefaultDPI;
+      : GetScalingFactorFromDPI(GetDPI().width());
 }
 
 }  // namespace
@@ -59,6 +59,10 @@ int GetDPIFromScalingFactor(float device_scaling_factor) {
   return kDefaultDPI * device_scaling_factor;
 }
 
+float GetScalingFactorFromDPI(int dpi) {
+  return static_cast<float>(dpi) / kDefaultDPI;
+}
+
 int GetSystemMetricsInDIP(int metric) {
   // The system metrics always reflect the system DPI, not whatever scale we've
   // forced or decided to use.