Make //mojo/services/network/interfaces/BUILD.gn reusable by consumers.

mojo/services/network/interfaces/BUILD.gn

 # 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.
 
 import("//build/module_args/mojo.gni")
-import("//third_party/mojo/src/mojo/public/tools/bindings/mojom.gni")
+import("$mojo_sdk_root/mojo/public/tools/bindings/mojom.gni")
 
 mojom("interfaces") {
   sources = [
     "cookie_store.mojom",
     "host_resolver.mojom",
     "http_connection.mojom",
     "http_message.mojom",
     "http_server.mojom",
     "net_address.mojom",
     "network_service.mojom",
     "tcp_bound_socket.mojom",
     "tcp_connected_socket.mojom",
     "tcp_server_socket.mojom",
     "udp_socket.mojom",
     "url_loader.mojom",
     "url_loader_interceptor.mojom",
     "web_socket.mojom",
   ]
 
-  deps = [
-    "//third_party/mojo/src/mojo/public/interfaces/network",
-  ]
+  mojo_sdk_deps = [ "mojo/public/interfaces/network" ]
 
   import_dirs = [
     get_path_info("../../", "abspath"),
-    "//third_party/mojo/src",
+    "$mojo_sdk_root",
   ]
 }