Implement gfx::Vector2d and gfx::Vector2dF StructTraits

ui/gfx/geometry/mojo/geometry_traits_test_service.mojom

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 module gfx.mojom;
 
 import "ui/gfx/geometry/mojo/geometry.mojom";
 
 // All functions on this interface echo their arguments to test StructTraits
 // serialization and deserialization.
@@ skipping 14 matching lines @@
   EchoRect(Rect r) => (Rect pass);
 
   [Sync]
   EchoRectF(RectF r) => (RectF pass);
 
   [Sync]
   EchoInsets(Insets i) => (Insets pass);
 
   [Sync]
   EchoInsetsF(InsetsF i) => (InsetsF pass);
+
+  [Sync]
+  EchoVector2d(Vector2d v) => (Vector2d pass);
+
+  [Sync]
+  EchoVector2dF(Vector2dF v) => (Vector2dF pass);
 };