Mandoline: Implement basic "process per site" support

mojo/services/network/public/interfaces/url_loader.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.
 
 module mojo;
 
 import "network/public/interfaces/http_message.mojom";
 import "network/public/interfaces/network_error.mojom";
 
 struct URLRequest {
@@ skipping 30 matching lines @@
   // If the response resulted in a network level error, this field will be set.
   NetworkError? error;
 
   // The response body stream. Read from this data pipe to receive the bytes of
   // response body.
   handle<data_pipe_consumer>? body;
 
   // The final URL of the response, after redirects have been followed.
   string? url;
 
+  // The site of the URL.
+  string? site;
+
   // The HTTP status code. 0 if not applicable.
   uint32 status_code;
 
   // The HTTP status line.
   string? status_line;
 
   // The HTTP response headers.
   array<HttpHeader>? headers;
 
   // The MIME type of the response body.
@@ skipping 31 matching lines @@
   Start(URLRequest request) => (URLResponse response);
 
   // If the request passed to |Start| had |auto_follow_redirects| set to false,
   // then upon receiving an URLResponse with a non-NULL |redirect_url| field,
   // |FollowRedirect| may be called to load the URL indicated by the redirect.
   FollowRedirect() => (URLResponse response);
 
   // Query status about the URLLoader.
   QueryStatus() => (URLLoaderStatus status);
 };