diff --git a/toolkit/devtools/server/actors/timeline.js b/toolkit/devtools/server/actors/timeline.js
index b92e44da4a97..9d562d8e6704 100644
--- a/toolkit/devtools/server/actors/timeline.js
+++ b/toolkit/devtools/server/actors/timeline.js
@@ -7,8 +7,7 @@
 /**
  * Many Gecko operations (painting, reflows, restyle, ...) can be tracked
  * in real time. A marker is a representation of one operation. A marker
- * has a name, and start and end timestamps. Markers are stored within
- * a docshell.
+ * has a name, and start and end timestamps. Markers are stored in docShells.
  *
  * This actor exposes this tracking mechanism to the devtools protocol.
  *
@@ -28,21 +27,24 @@ const {method, Arg, RetVal} = protocol;
 const events = require("sdk/event/core");
 const {setTimeout, clearTimeout} = require("sdk/timers");
 
+// How often do we pull markers from the docShells, and therefore, how often do
+// we send events to the front (knowing that when there are no markers in the
+// docShell, no event is sent).
 const DEFAULT_TIMELINE_DATA_PULL_TIMEOUT = 200; // ms
 
 /**
- * The timeline actor pops and forwards timeline markers registered in
- * a docshell.
+ * The timeline actor pops and forwards timeline markers registered in docshells.
  */
 let TimelineActor = exports.TimelineActor = protocol.ActorClass({
   typeName: "timeline",
 
   events: {
     /**
-     * "markers" events are emitted at regular intervals when profile markers
-     * are found. A marker has the following properties:
-     * - start {Number}
-     * - end {Number}
+     * "markers" events are emitted every DEFAULT_TIMELINE_DATA_PULL_TIMEOUT ms
+     * at most, when profile markers are found. A marker has the following
+     * properties:
+     * - start {Number} ms
+     * - end {Number} ms
      * - name {String}
      */
     "markers" : {
@@ -53,7 +55,13 @@ let TimelineActor = exports.TimelineActor = protocol.ActorClass({
 
   initialize: function(conn, tabActor) {
     protocol.Actor.prototype.initialize.call(this, conn);
-    this.docshell = tabActor.docShell;
+    this.tabActor = tabActor;
+
+    this._isRecording = false;
+
+    // Make sure to get markers from new windows as they become available
+    this._onWindowReady = this._onWindowReady.bind(this);
+    events.on(this.tabActor, "window-ready", this._onWindowReady);
   },
 
   /**
@@ -67,29 +75,57 @@ let TimelineActor = exports.TimelineActor = protocol.ActorClass({
 
   destroy: function() {
     this.stop();
-    this.docshell = null;
+
+    events.off(this.tabActor, "window-ready", this._onWindowReady);
+    this.tabActor = null;
+
     protocol.Actor.prototype.destroy.call(this);
   },
 
+  /**
+   * Convert a window to a docShell.
+   * @param {nsIDOMWindow}
+   * @return {nsIDocShell}
+   */
+  toDocShell: win => win.QueryInterface(Ci.nsIInterfaceRequestor)
+                        .getInterface(Ci.nsIWebNavigation)
+                        .QueryInterface(Ci.nsIDocShell),
+
+  /**
+   * Get the list of docShells in the currently attached tabActor.
+   * @return {Array}
+   */
+  get docShells() {
+    return this.tabActor.windows.map(this.toDocShell);
+  },
+
   /**
    * At regular intervals, pop the markers from the docshell, and forward
    * markers if any.
    */
   _pullTimelineData: function() {
-    let markers = this.docshell.popProfileTimelineMarkers();
+    if (!this._isRecording) {
+      return;
+    }
+
+    let markers = [];
+    for (let docShell of this.docShells) {
+      markers = [...markers, ...docShell.popProfileTimelineMarkers()];
+    }
     if (markers.length > 0) {
       events.emit(this, "markers", markers);
     }
+
     this._dataPullTimeout = setTimeout(() => {
       this._pullTimelineData();
     }, DEFAULT_TIMELINE_DATA_PULL_TIMEOUT);
   },
 
   /**
-   * Are we recording profile markers for the current docshell (window)?
+   * Are we recording profile markers currently?
    */
   isRecording: method(function() {
-    return this.docshell.recordProfileTimelineMarkers;
+    return this._isRecording;
   }, {
     request: {},
     response: {
@@ -98,21 +134,46 @@ let TimelineActor = exports.TimelineActor = protocol.ActorClass({
   }),
 
   /**
-   * Start/stop recording profile markers.
+   * Start recording profile markers.
    */
   start: method(function() {
-    if (!this.docshell.recordProfileTimelineMarkers) {
-      this.docshell.recordProfileTimelineMarkers = true;
-      this._pullTimelineData();
+    if (this._isRecording) {
+      return;
     }
+    this._isRecording = true;
+
+    for (let docShell of this.docShells) {
+      docShell.recordProfileTimelineMarkers = true;
+    }
+
+    this._pullTimelineData();
   }, {}),
 
+  /**
+   * Stop recording profile markers.
+   */
   stop: method(function() {
-    if (this.docshell.recordProfileTimelineMarkers) {
-      this.docshell.recordProfileTimelineMarkers = false;
-      clearTimeout(this._dataPullTimeout);
+    if (!this._isRecording) {
+      return;
     }
+    this._isRecording = false;
+
+    for (let docShell of this.docShells) {
+      docShell.recordProfileTimelineMarkers = false;
+    }
+
+    clearTimeout(this._dataPullTimeout);
   }, {}),
+
+  /**
+   * When a new window becomes available in the tabActor, start recording its
+   * markers if we were recording.
+   */
+  _onWindowReady: function({window}) {
+    if (this._isRecording) {
+      this.toDocShell(window).recordProfileTimelineMarkers = true;
+    }
+  }
 });
 
 exports.TimelineFront = protocol.FrontClass(TimelineActor, {
diff --git a/toolkit/devtools/server/tests/browser/browser.ini b/toolkit/devtools/server/tests/browser/browser.ini
index f981979665c9..6e20a3b9bd39 100644
--- a/toolkit/devtools/server/tests/browser/browser.ini
+++ b/toolkit/devtools/server/tests/browser/browser.ini
@@ -3,17 +3,21 @@ skip-if = e10s # Bug ?????? - devtools tests disabled with e10s
 subsuite = devtools
 support-files =
   head.js
+  navigate-first.html
+  navigate-second.html
   storage-dynamic-windows.html
   storage-listings.html
   storage-unsecured-iframe.html
   storage-updates.html
   storage-secured-iframe.html
-  navigate-first.html
-  navigate-second.html
+  timeline-iframe-child.html
+  timeline-iframe-parent.html
 
+[browser_navigateEvents.js]
 [browser_storage_dynamic_windows.js]
 [browser_storage_listings.js]
 [browser_storage_updates.js]
-[browser_navigateEvents.js]
 [browser_timeline.js]
 skip-if = buildapp == 'mulet'
+[browser_timeline_iframes.js]
+skip-if = buildapp == 'mulet'
diff --git a/toolkit/devtools/server/tests/browser/browser_navigateEvents.js b/toolkit/devtools/server/tests/browser/browser_navigateEvents.js
index 8dbf88bf1461..68487fd27dfc 100644
--- a/toolkit/devtools/server/tests/browser/browser_navigateEvents.js
+++ b/toolkit/devtools/server/tests/browser/browser_navigateEvents.js
@@ -1,17 +1,13 @@
+/* vim: set ft=javascript ts=2 et sw=2 tw=80: */
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
 
-let Cu = Components.utils;
-let Cc = Components.classes;
-let Ci = Components.interfaces;
+"use strict";
 
 const URL1 = MAIN_DOMAIN + "navigate-first.html";
 const URL2 = MAIN_DOMAIN + "navigate-second.html";
 
-let { DebuggerClient } = Cu.import("resource://gre/modules/devtools/dbg-client.jsm", {});
-let { DebuggerServer } = Cu.import("resource://gre/modules/devtools/dbg-server.jsm", {});
-
-let devtools = Cu.import("resource://gre/modules/devtools/Loader.jsm", {}).devtools;
-let events = devtools.require("sdk/event/core");
-
+let events = require("sdk/event/core");
 let client;
 
 // State machine to check events order
@@ -97,24 +93,18 @@ function onLoad() {
 
 function getServerTabActor(callback) {
   // Ensure having a minimal server
-  if (!DebuggerServer.initialized) {
-    DebuggerServer.init(function () { return true; });
-    DebuggerServer.addBrowserActors();
-  }
+  initDebuggerServer();
 
   // Connect to this tab
   let transport = DebuggerServer.connectPipe();
   client = new DebuggerClient(transport);
-  client.connect(function onConnect() {
-    client.listTabs(function onListTabs(aResponse) {
-      // Fetch the BrowserTabActor for this tab
-      let actorID = aResponse.tabs[aResponse.selected].actor;
-      client.attachTab(actorID, function(aResponse, aTabClient) {
-        // !Hack! Retrieve a server side object, the BrowserTabActor instance
-        let conn = transport._serverConnection;
-        let tabActor = conn.getActor(actorID);
-        callback(tabActor);
-      });
+  connectDebuggerClient(client).then(form => {
+    let actorID = form.actor;
+    client.attachTab(actorID, function(aResponse, aTabClient) {
+      // !Hack! Retrieve a server side object, the BrowserTabActor instance
+      let conn = transport._serverConnection;
+      let tabActor = conn.getActor(actorID);
+      callback(tabActor);
     });
   });
 
diff --git a/toolkit/devtools/server/tests/browser/browser_storage_dynamic_windows.js b/toolkit/devtools/server/tests/browser/browser_storage_dynamic_windows.js
index 795c4eb90f36..9c1f0a482bef 100644
--- a/toolkit/devtools/server/tests/browser/browser_storage_dynamic_windows.js
+++ b/toolkit/devtools/server/tests/browser/browser_storage_dynamic_windows.js
@@ -1,11 +1,8 @@
-const Cu = Components.utils;
-Cu.import("resource://gre/modules/Services.jsm");
-let tempScope = {};
-Cu.import("resource://gre/modules/devtools/dbg-client.jsm", tempScope);
-Cu.import("resource://gre/modules/devtools/dbg-server.jsm", tempScope);
-Cu.import("resource://gre/modules/Promise.jsm", tempScope);
-let {DebuggerServer, DebuggerClient, Promise} = tempScope;
-tempScope = null;
+/* vim: set ft=javascript ts=2 et sw=2 tw=80: */
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
 
 const {StorageFront} = require("devtools/server/actors/storage");
 let gFront, gWindow;
@@ -60,7 +57,7 @@ function finishTests(client) {
       forceCollections();
       DebuggerServer.destroy();
       forceCollections();
-      gFront = gWindow = DebuggerClient = DebuggerServer = null;
+      gFront = gWindow = null;
       finish();
     });
   }
@@ -306,23 +303,13 @@ function testRemoveIframe() {
 
 function test() {
   addTab(MAIN_DOMAIN + "storage-dynamic-windows.html").then(function(doc) {
-    try {
-      // Sometimes debugger server does not get destroyed correctly by previous
-      // tests.
-      DebuggerServer.destroy();
-    } catch (ex) { }
-    DebuggerServer.init(function () { return true; });
-    DebuggerServer.addBrowserActors();
+    initDebuggerServer();
 
     let createConnection = () => {
       let client = new DebuggerClient(DebuggerServer.connectPipe());
-      client.connect(function onConnect() {
-        client.listTabs(function onListTabs(aResponse) {
-          let form = aResponse.tabs[aResponse.selected];
-          gFront = StorageFront(client, form);
-
-          gFront.listStores().then(data => testStores(data, client));
-        });
+      connectDebuggerClient(client).then(form => {
+        gFront = StorageFront(client, form);
+        gFront.listStores().then(data => testStores(data, client));
       });
     };
 
diff --git a/toolkit/devtools/server/tests/browser/browser_storage_listings.js b/toolkit/devtools/server/tests/browser/browser_storage_listings.js
index f8da7c0de4a0..11c9b558d879 100644
--- a/toolkit/devtools/server/tests/browser/browser_storage_listings.js
+++ b/toolkit/devtools/server/tests/browser/browser_storage_listings.js
@@ -1,13 +1,10 @@
-const Cu = Components.utils;
-Cu.import("resource://gre/modules/Services.jsm");
-let tempScope = {};
-Cu.import("resource://gre/modules/devtools/dbg-client.jsm", tempScope);
-Cu.import("resource://gre/modules/devtools/dbg-server.jsm", tempScope);
-let {DebuggerServer, DebuggerClient} = tempScope;
-tempScope = null;
+/* vim: set ft=javascript ts=2 et sw=2 tw=80: */
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
 
 const {StorageFront} = require("devtools/server/actors/storage");
-let {Task} = require("resource://gre/modules/Task.jsm");
 let gWindow = null;
 
 const storeMap = {
@@ -348,7 +345,7 @@ function finishTests(client) {
       forceCollections();
       DebuggerServer.destroy();
       forceCollections();
-      gWindow = DebuggerClient = DebuggerServer = null;
+      gWindow = null;
       finish();
     });
   }
@@ -640,24 +637,14 @@ let testIDBEntries = Task.async(function*(index, hosts, indexedDBActor) {
 
 function test() {
   addTab(MAIN_DOMAIN + "storage-listings.html").then(function(doc) {
-    try {
-      // Sometimes debugger server does not get destroyed correctly by previous
-      // tests.
-      DebuggerServer.destroy();
-    } catch (ex) { }
-    DebuggerServer.init(function () { return true; });
-    DebuggerServer.addBrowserActors();
+    initDebuggerServer();
 
     let createConnection = () => {
       let client = new DebuggerClient(DebuggerServer.connectPipe());
-      client.connect(function onConnect() {
-        client.listTabs(function onListTabs(aResponse) {
-          let form = aResponse.tabs[aResponse.selected];
-          let front = StorageFront(client, form);
-
-          front.listStores().then(data => testStores(data))
-               .then(() => finishTests(client));
-        });
+      connectDebuggerClient(client).then(form => {
+        let front = StorageFront(client, form);
+        front.listStores().then(data => testStores(data))
+                          .then(() => finishTests(client));
       });
     };
 
diff --git a/toolkit/devtools/server/tests/browser/browser_storage_updates.js b/toolkit/devtools/server/tests/browser/browser_storage_updates.js
index 6ff18ce9270b..0af662150499 100644
--- a/toolkit/devtools/server/tests/browser/browser_storage_updates.js
+++ b/toolkit/devtools/server/tests/browser/browser_storage_updates.js
@@ -1,11 +1,8 @@
-const Cu = Components.utils;
-Cu.import("resource://gre/modules/Services.jsm");
-let tempScope = {};
-Cu.import("resource://gre/modules/devtools/dbg-client.jsm", tempScope);
-Cu.import("resource://gre/modules/devtools/dbg-server.jsm", tempScope);
-Cu.import("resource://gre/modules/Promise.jsm", tempScope);
-let {DebuggerServer, DebuggerClient, Promise} = tempScope;
-tempScope = null;
+/* vim: set ft=javascript ts=2 et sw=2 tw=80: */
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
 
 const {StorageFront} = require("devtools/server/actors/storage");
 let gTests;
@@ -25,7 +22,7 @@ function finishTests(client) {
     forceCollections();
     DebuggerServer.destroy();
     forceCollections();
-    DebuggerClient = DebuggerServer = gTests = null;
+    gTests = null;
     finish();
   });
 }
@@ -232,24 +229,15 @@ function* UpdateTests(front, win, client) {
 
 function test() {
   addTab(MAIN_DOMAIN + "storage-updates.html").then(function(doc) {
-    try {
-      // Sometimes debugger server does not get destroyed correctly by previous
-      // tests.
-      DebuggerServer.destroy();
-    } catch (ex) { }
-    DebuggerServer.init(function () { return true; });
-    DebuggerServer.addBrowserActors();
+    initDebuggerServer();
 
     let client = new DebuggerClient(DebuggerServer.connectPipe());
-    client.connect(function onConnect() {
-      client.listTabs(function onListTabs(aResponse) {
-        let form = aResponse.tabs[aResponse.selected];
-        let front = StorageFront(client, form);
-        gTests = UpdateTests(front, doc.defaultView.wrappedJSObject,
-                             client);
-        // Make an initial call to initialize the actor
-        front.listStores().then(() => gTests.next());
-      });
+    connectDebuggerClient(client).then(form => {
+      let front = StorageFront(client, form);
+      gTests = UpdateTests(front, doc.defaultView.wrappedJSObject,
+                           client);
+      // Make an initial call to initialize the actor
+      front.listStores().then(() => gTests.next());
     });
   })
 }
diff --git a/toolkit/devtools/server/tests/browser/browser_timeline.js b/toolkit/devtools/server/tests/browser/browser_timeline.js
index bc805756abbf..35833b95dcc8 100644
--- a/toolkit/devtools/server/tests/browser/browser_timeline.js
+++ b/toolkit/devtools/server/tests/browser/browser_timeline.js
@@ -1,29 +1,21 @@
 /* vim: set ft=javascript ts=2 et sw=2 tw=80: */
 /* Any copyright is dedicated to the Public Domain.
    http://creativecommons.org/publicdomain/zero/1.0/ */
+
 "use strict";
 
-let test = asyncTest(function*() {
-  const {TimelineFront} = require("devtools/server/actors/timeline");
-  const Cu = Components.utils;
-  let tempScope = {};
-  Cu.import("resource://gre/modules/devtools/dbg-client.jsm", tempScope);
-  Cu.import("resource://gre/modules/devtools/dbg-server.jsm", tempScope);
-  let {DebuggerServer, DebuggerClient} = tempScope;
+// Test that the timeline front's start/stop/isRecording methods work in a
+// simple use case, and that markers events are sent when operations occur.
 
+const {TimelineFront} = require("devtools/server/actors/timeline");
+
+let test = asyncTest(function*() {
   let doc = yield addTab("data:text/html;charset=utf-8,mop");
 
-  DebuggerServer.init(function () { return true; });
-  DebuggerServer.addBrowserActors();
+  initDebuggerServer();
   let client = new DebuggerClient(DebuggerServer.connectPipe());
-  let onListTabs = promise.defer();
-  client.connect(() => {
-    client.listTabs(onListTabs.resolve);
-  });
 
-  let listTabs = yield onListTabs.promise;
-
-  let form = listTabs.tabs[listTabs.selected];
+  let form = yield connectDebuggerClient(client);
   let front = TimelineFront(client, form);
 
   let isActive = yield front.isRecording();
@@ -59,9 +51,6 @@ let test = asyncTest(function*() {
   isActive = yield front.isRecording();
   ok(!isActive, "Not recording after stop()");
 
-  let onClose = promise.defer();
-  client.close(onClose.resolve);
-  yield onClose;
-
+  yield closeDebuggerClient(client);
   gBrowser.removeCurrentTab();
 });
diff --git a/toolkit/devtools/server/tests/browser/browser_timeline_iframes.js b/toolkit/devtools/server/tests/browser/browser_timeline_iframes.js
new file mode 100644
index 000000000000..441500370bb0
--- /dev/null
+++ b/toolkit/devtools/server/tests/browser/browser_timeline_iframes.js
@@ -0,0 +1,41 @@
+/* vim: set ft=javascript ts=2 et sw=2 tw=80: */
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test the timeline front receives markers events for operations that occur in
+// iframes.
+
+const {TimelineFront} = require("devtools/server/actors/timeline");
+
+let test = asyncTest(function*() {
+  let doc = yield addTab(MAIN_DOMAIN + "timeline-iframe-parent.html");
+
+  initDebuggerServer();
+  let client = new DebuggerClient(DebuggerServer.connectPipe());
+  let form = yield connectDebuggerClient(client);
+  let front = TimelineFront(client, form);
+
+  info("Start timeline marker recording");
+  yield front.start();
+
+  // Check that we get markers for a few iterations of the timer that runs in
+  // the child frame.
+  for (let i = 0; i < 3; i ++) {
+    yield wait(300); // That's the time the child frame waits before changing styles.
+    let markers = yield once(front, "markers");
+    ok(markers.length, "Markers were received for operations in the child frame");
+  }
+
+  info("Stop timeline marker recording");
+  yield front.stop();
+  yield closeDebuggerClient(client);
+  gBrowser.removeCurrentTab();
+});
+
+function wait(ms) {
+  let def = promise.defer();
+  setTimeout(def.resolve, ms);
+  return def.promise;
+}
diff --git a/toolkit/devtools/server/tests/browser/head.js b/toolkit/devtools/server/tests/browser/head.js
index d4008f6dc903..02e419ea9e63 100644
--- a/toolkit/devtools/server/tests/browser/head.js
+++ b/toolkit/devtools/server/tests/browser/head.js
@@ -1,23 +1,28 @@
 /* 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/. */
-let tempScope = {};
-Cu.import("resource://gre/modules/devtools/Loader.jsm", tempScope);
-Cu.import("resource://gre/modules/devtools/Console.jsm", tempScope);
-const require = tempScope.devtools.require;
-const console = tempScope.console;
-tempScope = null;
+
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+const Cu = Components.utils;
+
+Cu.import("resource://gre/modules/Services.jsm");
+const {console} = Cu.import("resource://gre/modules/devtools/Console.jsm", {});
+const {Promise: promise} = Cu.import("resource://gre/modules/Promise.jsm", {});
+const {devtools: {require}} = Cu.import("resource://gre/modules/devtools/Loader.jsm", {});
+const {DebuggerClient} = Cu.import("resource://gre/modules/devtools/dbg-client.jsm", {});
+const {DebuggerServer} = Cu.import("resource://gre/modules/devtools/dbg-server.jsm", {});
+
 const PATH = "browser/toolkit/devtools/server/tests/browser/";
 const MAIN_DOMAIN = "http://test1.example.org/" + PATH;
 const ALT_DOMAIN = "http://sectest1.example.org/" + PATH;
 const ALT_DOMAIN_SECURED = "https://sectest1.example.org:443/" + PATH;
-const { Promise: promise } = Cu.import("resource://gre/modules/Promise.jsm", {});
 
-// All test are asynchronous
+// All tests are asynchronous.
 waitForExplicitFinish();
 
 /**
- * Define an async test based on a generator function
+ * Define an async test based on a generator function.
  */
 function asyncTest(generator) {
   return () => Task.spawn(generator).then(null, ok.bind(null, false)).then(finish);
@@ -47,6 +52,43 @@ let addTab = Task.async(function* (url) {
   return tab.linkedBrowser.contentWindow.document;
 });
 
+function initDebuggerServer() {
+  try {
+    // Sometimes debugger server does not get destroyed correctly by previous
+    // tests.
+    DebuggerServer.destroy();
+  } catch (ex) { }
+  DebuggerServer.init(() => true);
+  DebuggerServer.addBrowserActors();
+}
+
+/**
+ * Connect a debugger client.
+ * @param {DebuggerClient}
+ * @return {Promise} Resolves to the selected tabActor form when the client is
+ * connected.
+ */
+function connectDebuggerClient(client) {
+  let def = promise.defer();
+  client.connect(() => {
+    client.listTabs(tabs => {
+      def.resolve(tabs.tabs[tabs.selected]);
+    });
+  });
+  return def.promise;
+}
+
+/**
+ * Close a debugger client's connection.
+ * @param {DebuggerClient}
+ * @return {Promise} Resolves when the connection is closed.
+ */
+function closeDebuggerClient(client) {
+  let def = promise.defer();
+  client.close(def.resolve);
+  return def.promise;
+}
+
 /**
  * Wait for eventName on target.
  * @param {Object} target An observable object that either supports on/off or
diff --git a/toolkit/devtools/server/tests/browser/timeline-iframe-child.html b/toolkit/devtools/server/tests/browser/timeline-iframe-child.html
new file mode 100644
index 000000000000..5385c64859eb
--- /dev/null
+++ b/toolkit/devtools/server/tests/browser/timeline-iframe-child.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Timeline iframe test - child frame</title>
+</head>
+<body>
+  <h1>Child frame</h1>
+  <script>
+    var h1 = document.querySelector("h1");
+    setInterval(function() {
+      h1.style.backgroundColor = "rgb(" + ((Math.random()*255)|0) + "," +
+                                          ((Math.random()*255)|0) + "," +
+                                          ((Math.random()*255)|0) +")";
+      h1.style.width = ((Math.random()*500)|0) + "px";
+    }, 300);
+  </script>
+</body>
+</html>
diff --git a/toolkit/devtools/server/tests/browser/timeline-iframe-parent.html b/toolkit/devtools/server/tests/browser/timeline-iframe-parent.html
new file mode 100644
index 000000000000..b94ba42597ad
--- /dev/null
+++ b/toolkit/devtools/server/tests/browser/timeline-iframe-parent.html
@@ -0,0 +1,11 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Timeline iframe test - parent frame</title>
+</head>
+<body>
+  <h1>Parent frame</h1>
+  <iframe src="timeline-iframe-child.html"></iframe>
+</body>
+</html>