--- a/toolkit/components/extensions/test/mochitest/test_ext_webrequest_background_events.html
+++ b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_background_events.html
@@ -77,16 +77,17 @@ add_task(async function test_webRequest_
         "onCompleted",
       ]);
 
       function listener(name, details) {
         browser.test.assertTrue(eventNames.has(name), `recieved ${name}`);
         eventNames.delete(name);
 
         if (eventNames.size === 0) {
+          browser.test.assertEq("xmlhttprequest", details.type, "correct type for fetch [bug 1366710]");
           browser.test.assertEq(0, eventNames.size, "messages recieved");
           browser.test.sendMessage("done");
         }
       }
 
       for (let name of eventNames) {
         browser.webRequest[name].addListener(
           listener.bind(null, name),

--- a/toolkit/components/extensions/test/mochitest/test_ext_webrequest_filter.html
+++ b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_filter.html
@@ -167,17 +167,17 @@ add_task(async function test_webRequest_
   let expect = {
     "webrequest_worker.js": {
       type: "script",
     },
     "example.txt": {
       status: 404,
       events: ["onBeforeRequest", "onBeforeSendHeaders", "onSendHeaders", "onHeadersReceived", "onResponseStarted"],
       optional_events: ["onCompleted", "onErrorOccurred"],
-      type: "other",
+      type: "xmlhttprequest",
       origin: SimpleTest.getTestFileURL("webrequest_worker.js?test2"),
     },
   };
 
   let extension = makeExtension(events);
   await extension.startup();
   extension.sendMessage("set-expected", {expect, origin: location.href});
   await extension.awaitMessage("continue");

--- a/toolkit/modules/addons/WebRequestCommon.jsm
+++ b/toolkit/modules/addons/WebRequestCommon.jsm
@@ -19,16 +19,18 @@ var WebRequestCommon = {
       case Ci.nsIContentPolicy.TYPE_DOCUMENT: return "main_frame";
       case Ci.nsIContentPolicy.TYPE_SUBDOCUMENT: return "sub_frame";
       case Ci.nsIContentPolicy.TYPE_STYLESHEET: return "stylesheet";
       case Ci.nsIContentPolicy.TYPE_SCRIPT: return "script";
       case Ci.nsIContentPolicy.TYPE_IMAGE: return "image";
       case Ci.nsIContentPolicy.TYPE_OBJECT: return "object";
       case Ci.nsIContentPolicy.TYPE_OBJECT_SUBREQUEST: return "object_subrequest";
       case Ci.nsIContentPolicy.TYPE_XMLHTTPREQUEST: return "xmlhttprequest";
+      // TYPE_FETCH returns xmlhttprequest for cross-browser compatibility.
+      case Ci.nsIContentPolicy.TYPE_FETCH: return "xmlhttprequest";
       case Ci.nsIContentPolicy.TYPE_XBL: return "xbl";
       case Ci.nsIContentPolicy.TYPE_XSLT: return "xslt";
       case Ci.nsIContentPolicy.TYPE_PING: return "ping";
       case Ci.nsIContentPolicy.TYPE_BEACON: return "beacon";
       case Ci.nsIContentPolicy.TYPE_DTD: return "xml_dtd";
       case Ci.nsIContentPolicy.TYPE_FONT: return "font";
       case Ci.nsIContentPolicy.TYPE_MEDIA: return "media";
       case Ci.nsIContentPolicy.TYPE_WEBSOCKET: return "websocket";