Mandoline: Implement basic "process per site" support

mojo/services/network/public/interfaces/url_loader.mojom

Index: mojo/services/network/public/interfaces/url_loader.mojom
diff --git a/mojo/services/network/public/interfaces/url_loader.mojom b/mojo/services/network/public/interfaces/url_loader.mojom
index d0a7164246c086b08007dccbb31a5eb17c4e8333..abb21f2080870bc6c449f61b875fc36fdb91edfe 100644
--- a/mojo/services/network/public/interfaces/url_loader.mojom
+++ b/mojo/services/network/public/interfaces/url_loader.mojom
@@ -48,6 +48,10 @@ struct URLResponse {
   // The final URL of the response, after redirects have been followed.
   string? url;
 
+  // The site of the URL used for determine what process this resource should

[jam, 2015/07/10 16:12:00]

nit: since this a generic fetch api, better not to say how this variable is used
by the shell. i.e. just "// The site of the URL."

[Fady Samuel, 2015/07/10 16:16:08]

Done.

+  // live in.
+  string? site;
+
   // The HTTP status code. 0 if not applicable.
   uint32 status_code;