ui: Make gfx::Size::Scale() mutate the class. Add gfx::ScaleSize() similar to Rect/Point.

ui/gfx/size.h

Index: ui/gfx/size.h
diff --git a/ui/gfx/size.h b/ui/gfx/size.h
index 4425207a18fa4b25b3a8bb433a4bd7b9da9940a8..a525251b648ebe294e7827952fd195ac28c91f37 100644
--- a/ui/gfx/size.h
+++ b/ui/gfx/size.h
@@ -47,14 +47,6 @@ class UI_EXPORT Size : public SizeBase<Size, int> {
     return SizeF(width(), height());
   }
 
-  SizeF Scale(float scale) const WARN_UNUSED_RESULT {
-    return Scale(scale, scale);
-  }
-
-  SizeF Scale(float x_scale, float y_scale) const WARN_UNUSED_RESULT {
-    return SizeF(width() * x_scale, height() * y_scale);
-  }
-
   std::string ToString() const;
 };