Don't return unsupported scales frrom GetScaleFactorFromScale()

ui/base/layout.h

Index: ui/base/layout.h
diff --git a/ui/base/layout.h b/ui/base/layout.h
index f8836a06c29ce76147b0470788069272de4824ce..3992189ee8a847107ad0c4bd4b4e428c88109042 100644
--- a/ui/base/layout.h
+++ b/ui/base/layout.h
@@ -48,7 +48,7 @@ enum ScaleFactor {
 // Returns the float scale value for |scale_factor|.
 UI_EXPORT float GetScaleFactorScale(ScaleFactor scale_factor);
 
-// Returns the ScaleFactor which most closely matches |scale|.
+// Returns the supported ScaleFactor which most closely matches |scale|.
 // Converting from float to ScaleFactor is inefficient and should be done as
 // little as possible.
 UI_EXPORT ScaleFactor GetScaleFactorFromScale(float scale);