Implement MIME sniffing.

components/net/data_loader.rs

@@ -96,7 +96,7 @@ fn assert_parse(url:          &'static str,
     use sniffer_task;
 
     let (start_chan, start_port) = channel();
-    let sniffer_task = sniffer_task::new_sniffer_task();
+    let sniffer_task = sniffer_task::new_mock_sniffer_task();
     load(LoadData::new(Url::parse(url).unwrap(), start_chan), sniffer_task);
 
     let response = start_port.recv().unwrap();

components/net/lib.rs

@@ -47,6 +47,7 @@ pub mod pub_domains;
 pub mod resource_task;
 pub mod storage_task;
 mod sniffer_task;
+mod mime_classifier;
 
 /// An implementation of the [Fetch spec](http://fetch.spec.whatwg.org/)
 pub mod fetch {