For some vector icons, get the size from the vector definition.

ui/gfx/paint_vector_icon.h

Index: ui/gfx/paint_vector_icon.h
diff --git a/ui/gfx/paint_vector_icon.h b/ui/gfx/paint_vector_icon.h
index a9adb797e6ab39da0b629942fba3b3ec07a74f2b..5dbf66cfff5c234812737b24ef27c300c01b5aae 100644
--- a/ui/gfx/paint_vector_icon.h
+++ b/ui/gfx/paint_vector_icon.h
@@ -24,7 +24,12 @@ GFX_EXPORT void PaintVectorIcon(Canvas* canvas,
                                 size_t dip_size,
                                 SkColor color);
 
-// Creates an ImageSkia which will render the icon on demand.
+// Creates an ImageSkia which will render the icon on demand. The size will come
+// from the .icon file (the 1x version, if multiple versions exist).
+GFX_EXPORT ImageSkia CreateVectorIcon(VectorIconId id,
+                                      SkColor color);
+
+// As above, but creates the image at the given size.
 GFX_EXPORT ImageSkia CreateVectorIcon(VectorIconId id,
                                       size_t dip_size,
                                       SkColor color);