Uses and returns the fractional width in text eliding

ui/gfx/rect_f.h

Index: ui/gfx/rect_f.h
diff --git a/ui/gfx/rect_f.h b/ui/gfx/rect_f.h
index 09de529a6278eb46adeaf6b9bd5ba556b9b8a74c..42b9cfba0ad3992c3c35c7ff389facb6ff567366 100644
--- a/ui/gfx/rect_f.h
+++ b/ui/gfx/rect_f.h
@@ -12,6 +12,12 @@
 #include "ui/gfx/size_f.h"
 #include "ui/gfx/vector2d_f.h"
 
+#if defined(OS_IOS)
+#include <CoreGraphics/CoreGraphics.h>
+#elif defined(OS_MACOSX)
+#include <ApplicationServices/ApplicationServices.h>
+#endif
+
 namespace gfx {
 
 class InsetsF;
@@ -42,6 +48,11 @@ class GFX_EXPORT RectF
 
   ~RectF() {}
 
+#if defined(OS_MACOSX)
+  // Construct an equivalent CoreGraphics object.
+  CGRect ToCGRect() const;
+#endif
+
   // Scales the rectangle by |scale|.
   void Scale(float scale) {
     Scale(scale, scale);