auto merge of #5219 : doublec/servo/view_source_protocol_and_plain_text, r=jdm

Implements view-source protocol by having a view-source handler, and modifying the content type to be text/plain if that is used. 

Implements text/plain handling. This allows view-source content to display as plain text.

Example usage:

    ./mach run http://cd.pn/x.txt
    ./mach run view-source:http://tinyvid.tv/

This fixes issue #4181. Issue #3649 includes "support text/plain" so this possibly fixes some of that issue as well.

components/net/http_loader.rs

@@ -14,6 +14,7 @@ use hyper::client::Request;
 use hyper::header::{ContentLength, ContentType, Host, Location};
 use hyper::HttpError;
 use hyper::method::Method;
+use hyper::mime::{Mime, TopLevel, SubLevel};
 use hyper::net::HttpConnector;
 use hyper::status::{StatusCode, StatusClass};
 use std::error::Error;
@@ -59,6 +60,26 @@ fn load(mut load_data: LoadData, start_chan: Sender<TargetedLoadResponse>, cooki
         eventual_consumer: load_data.consumer
     };
 
+    // If the URL is a view-source scheme then the scheme data contains the
+    // real URL that should be used for which the source is to be viewed.
+    // Change our existing URL to that and keep note that we are viewing
+    // the source rather than rendering the contents of the URL.
+    let viewing_source = if url.scheme == "view-source" {
+       let inner_url = load_data.url.non_relative_scheme_data().unwrap();
+       url = Url::parse(inner_url).unwrap();
+       match url.scheme.as_slice() {
+           "http" | "https" => {}
+           _ => {
+               let s = format!("The {} scheme with view-source is not supported", url.scheme);
+               send_error(url, s, senders);
+               return;
+           }
+       };
+       true
+    } else {
+      false
+    };
+
     // Loop to handle redirects.
     loop {
         iters = iters + 1;
@@ -259,12 +280,16 @@ reason: \"certificate verify failed\" }]";
             }
         }
 
+        let mut adjusted_headers = response.headers.clone();
+        if viewing_source {
+            adjusted_headers.set(ContentType(Mime(TopLevel::Text, SubLevel::Plain, vec![])));
+        }
         let mut metadata = Metadata::default(url);
-        metadata.set_content_type(match response.headers.get() {
+        metadata.set_content_type(match adjusted_headers.get() {
             Some(&ContentType(ref mime)) => Some(mime),
             None => None
         });
-        metadata.headers = Some(response.headers.clone());
+        metadata.headers = Some(adjusted_headers);
         metadata.status = Some(response.status_raw().clone());
 
         let progress_chan = match start_sending_opt(senders, metadata) {

components/net/resource_task.rs

@@ -333,7 +333,7 @@ impl ResourceManager {
 
         let loader = match load_data.url.scheme.as_slice() {
             "file" => from_factory(file_loader::factory),
-            "http" | "https" => http_loader::factory(self.resource_task.clone()),
+            "http" | "https" | "view-source" => http_loader::factory(self.resource_task.clone()),
             "data" => from_factory(data_loader::factory),
             "about" => from_factory(about_loader::factory),
             _ => {