Struct traits for gfx::Range and gfx::RangeF.

ui/gfx/BUILD.gn

Index: ui/gfx/BUILD.gn
diff --git a/ui/gfx/BUILD.gn b/ui/gfx/BUILD.gn
index 58562bdee865286d804a09733b97e683ec778e42..1e345fa28c9955a5a3c8f4970fedd3e56a8be546 100644
--- a/ui/gfx/BUILD.gn
+++ b/ui/gfx/BUILD.gn
@@ -704,6 +704,7 @@ test("gfx_unittests") {
       "//mojo/public/cpp/bindings",
       "//ui/gfx/geometry/mojo:unit_test",
       "//ui/gfx/mojo:test_interfaces",
+      "//ui/gfx/range/mojo:unit_test",
     ]
   }
 }