Ensure that extension resources are loaded with the correct scaling applied on Windows.

ui/base/layout.h

Index: ui/base/layout.h
diff --git a/ui/base/layout.h b/ui/base/layout.h
index 2ea39a289e2cb482e0d658629f232096dde4738d..cefeaa51dd2cdb0e76e314ec4dae04c0a8661edf 100644
--- a/ui/base/layout.h
+++ b/ui/base/layout.h
@@ -47,6 +47,9 @@ enum ScaleFactor {
   NUM_SCALE_FACTORS  // This always appears last.
 };
 
+// List of scales for each scale factor defined above
+extern float g_kScaleFactorScales[NUM_SCALE_FACTORS];

[sky, 2014/03/27 15:43:07]

I don't like exposing this. For one it isn't const, which may be problematic.
How about a function GetScaleForScaleFactor()?

[ananta, 2014/03/27 19:05:07]

Done.

+
 // Changes the value of GetSupportedScaleFactors() to |scale_factors|.
 // Use ScopedSetSupportedScaleFactors for unit tests as not to affect the
 // state of other tests.
@@ -57,7 +60,8 @@ UI_BASE_EXPORT void SetSupportedScaleFactors(
 // platform, in ascending order.
 UI_BASE_EXPORT const std::vector<ScaleFactor>& GetSupportedScaleFactors();
 
-// Returns the float scale value for |scale_factor|.
+// Returns the actual image scale to be used for the scale factor passed in.
+// On Windows high dpi, this returns the dpi scale for the display.
 UI_BASE_EXPORT float GetImageScale(ScaleFactor scale_factor);
 
 // Returns the supported ScaleFactor which most closely matches |scale|.