Fix Mojo and Mandoline builds.

mandoline/services/navigation/public/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("$mojo_sdk_root/mojo/public/tools/bindings/mojom.gni")
 
 mojom("interfaces") {
   sources = [
     "navigation.mojom",
   ]
 
+  import_dirs = [ mojo_network_service_root ]
+
   deps = [
     "//mojo/services/network/public/interfaces",
   ]
 }