Ensure that the extension icons show up in the omnibox at fractional scales.

ui/base/layout.h

Index: ui/base/layout.h
diff --git a/ui/base/layout.h b/ui/base/layout.h
index ab838780c25b278d8c2611f372255892c030126d..c0ca3cb65e4b08b546d4b43c1f5d454082e791db 100644
--- a/ui/base/layout.h
+++ b/ui/base/layout.h
@@ -54,6 +54,10 @@ UI_BASE_EXPORT float GetScaleFactorForNativeView(gfx::NativeView view);
 // Returns the image scale for the scale factor passed in.
 UI_BASE_EXPORT float GetScaleForScaleFactor(ScaleFactor scale_factor);
 
+// Returns true if the scale passed in is the list of supported scales for
+// the platform.
+UI_BASE_EXPORT bool IsSupportedScale(float scale);
+
 namespace test {
 // Class which changes the value of GetSupportedScaleFactors() to
 // |new_scale_factors| for the duration of its lifetime.