Uses mojom module names as Dart's package: import URI

mojo/services/gpu/public/interfaces/gpu.mojom

 // Copyright 2014 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.
 
+[DartUriBase="mojo/services/gpu/public/interfaces"]
 module mojo;
 
 import "gpu/public/interfaces/command_buffer.mojom";
 
 interface Gpu {
   // Creates a new offscreen OpenGL ES 2.0 context.
   CreateOffscreenGLES2Context(CommandBuffer& gles2_client);
 };