Update view manager to support content handling.

mojo/services/public/interfaces/content_handler/content_handler.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.
 
 import "mojo/public/interfaces/application/service_provider.mojom"
 import "mojo/services/public/interfaces/network/url_loader.mojom"
 
 module mojo {
 
+struct ContentHandlerResponse {
+  URLLoader loader;
+  URLResponse response;
+};
+
 interface ContentHandler {
   OnConnect(string url,
-            URLResponse url_response,
-            ServiceProvider service_provider);
+            ContentHandlerResponse response,
+            ServiceProvider&? service_provider);
 };
 
 }