Move mojom definitions of URL{Request,Response} into SDK

mojo/services/content_handler/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 = [
     "content_handler.mojom",
   ]
 
   import_dirs = [ get_path_info("../../../", "abspath") ]
 
-  if (defined(mojo_network_service_root)) {
-    import_dirs += [ mojo_network_service_root ]
-  } else {
-    mojo_network_service_root = "../../.."
-  }
-
-  deps = [
-    "$mojo_network_service_root/network/public/interfaces",
+  mojo_sdk_deps = [
+    "mojo/public/interfaces/application",
+    "mojo/public/interfaces/network",
   ]
-
-  mojo_sdk_deps = [ "mojo/public/interfaces/application" ]
 }