Remove IsHighDPIEnabled, move EnableHighDPISupport to only place it's used

ui/gfx/win/dpi.h

Index: ui/gfx/win/dpi.h
diff --git a/ui/gfx/win/dpi.h b/ui/gfx/win/dpi.h
index 8c39ab9e87943e4b5391d3ebf3611cc32ec99496..02c798ca16a545fbe8a0988a027a25c0e5d1c815 100644
--- a/ui/gfx/win/dpi.h
+++ b/ui/gfx/win/dpi.h
@@ -25,11 +25,6 @@ GFX_EXPORT Size GetDPI();
 // 96 then the scale factor is 1.0.
 GFX_EXPORT float GetDPIScale();
 
-// Tests to see if the command line flag "--high-dpi-support" is set.
-GFX_EXPORT bool IsHighDPIEnabled();
-
-GFX_EXPORT void EnableHighDPISupport();
-
 namespace win {
 
 GFX_EXPORT Point ScreenToDIPPoint(const Point& pixel_point);
@@ -50,9 +45,6 @@ GFX_EXPORT Size DIPToScreenSize(const Size& dip_size);
 // GetSystemMetrics for the given |metric|, then converts the result to DIP.
 GFX_EXPORT int GetSystemMetricsInDIP(int metric);
 
-GFX_EXPORT extern const wchar_t kRegistryProfilePath[];
-GFX_EXPORT extern const wchar_t kHighDPISupportW[];
-
 }  // namespace win
 }  // namespace gfx