Bug 1411725 - have XHR responseURL use the final channel URL so the expected URLs for substituted protocols like web-extension: are returned; r=mayhemer

have XHR responseURL use the final channel URL so the expected URLs for substituted protocols like web-extension: are returned

Differential Revision: https://phabricator.services.mozilla.com/D23811

--HG--
extra : moz-landing-system : lando

dom/xhr/XMLHttpRequestMainThread.cpp

@@ -783,9 +783,7 @@ void XMLHttpRequestMainThread::GetResponseURL(nsAString& aUrl) {
   }
 
   nsCOMPtr<nsIURI> responseUrl;
-  mChannel->GetURI(getter_AddRefs(responseUrl));
-
-  if (!responseUrl) {
+  if (NS_FAILED(NS_GetFinalChannelURI(mChannel, getter_AddRefs(responseUrl)))) {
     return;
   }
 

dom/xhr/tests/browser.ini

@@ -3,5 +3,6 @@ support-files =
   browser_xhr_onchange_leak.html
 [browser_blobFromFile.js]
 [browser_xhr_onchange_leak.js]
+[browser_xhr_substituted_protocol_responseURL.js]
 [browser_temporaryFile.js]
 support-files =  temporaryFileBlob.sjs

dom/xhr/tests/browser_xhr_substituted_protocol_responseURL.js

@@ -0,0 +1,23 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+// Bug 1411725 - An XHR using a SubstitutingProtocolHandler channel
+// (web-extension:, resource:, etc) should return the original URL,
+// not the jar/file it was actually substituted for.
+
+const TEST_URL = "resource://gre/modules/XPCOMUtils.jsm";
+
+add_task(async function test() {
+  await new Promise(resolve => {
+    const xhr = new XMLHttpRequest();
+    xhr.responseType = "text";
+    xhr.open("get", TEST_URL);
+    xhr.addEventListener("loadend", () => {
+      is(xhr.responseURL, TEST_URL, "original URL is given instead of substitution");
+      resolve();
+    });
+    xhr.send();
+  });
+});