Add a UMA histogram for a user's device scale at startup.

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 778d83b0d468dc2cd082e98831514f6fe6b3ddb1..1a44dc748f4517895ef8640fa6a9a13eec801584 100644
--- a/ui/display/win/dpi.cc
+++ b/ui/display/win/dpi.cc
@@ -35,12 +35,6 @@ gfx::Size GetDPI() {
   return gfx::Size(dpi_x, dpi_y);
 }
 
-float GetUnforcedDeviceScaleFactor() {
-  return g_device_scale_factor
-      ? g_device_scale_factor
-      : GetScalingFactorFromDPI(GetDPI().width());
-}
-
 }  // namespace
 
 void SetDefaultDeviceScaleFactor(float scale) {
@@ -48,6 +42,11 @@ void SetDefaultDeviceScaleFactor(float scale) {
   g_device_scale_factor = scale;
 }
 
+float GetUnforcedDeviceScaleFactor() {
+  return g_device_scale_factor ? g_device_scale_factor
+                               : GetScalingFactorFromDPI(GetDPI().width());
+}
+
 float GetDPIScale() {
   if (display::Display::HasForceDeviceScaleFactor())
     return display::Display::GetForcedDeviceScaleFactor();