Bug 1566870 - Fix FormAutoFill leak when focusing input in HTML frame r=kmag,MattN

Cleaning the FormAutofillContent on blur seems to fix the leak.

Differential Revision: https://phabricator.services.mozilla.com/D39716

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

browser/extensions/formautofill/content/FormAutofillFrameScript.js

@@ -60,6 +60,7 @@ var FormAutofillFrameScript = {
 
   init() {
     addEventListener("focusin", this);
+    addEventListener("focusout", this);
     addEventListener("DOMFormBeforeSubmit", this);
     addMessageListener("FormAutofill:PreviewProfile", this);
     addMessageListener("FormAutofill:ClearForm", this);
@@ -77,6 +78,10 @@ var FormAutofillFrameScript = {
         this.onFocusIn(evt);
         break;
       }
+      case "focusout": {
+        this.onFocusOut();
+        break;
+      }
       case "DOMFormBeforeSubmit": {
         this.onDOMFormBeforeSubmit(evt);
         break;
@@ -115,6 +120,12 @@ var FormAutofillFrameScript = {
     this._doIdentifyAutofillFields();
   },
 
+  onFocusOut() {
+    // Update active input on blur to release references on the previously
+    // focused element in FormAutofillContent.
+    FormAutofillContent.updateActiveInput();
+  },
+
   /**
    * Handle the DOMFormBeforeSubmit event.
    * @param {Event} evt

browser/extensions/formautofill/moz.build

@@ -37,6 +37,7 @@ TESTING_JS_MODULES += ['test/fixtures/OSKeyStoreTestUtils.jsm']
 BROWSER_CHROME_MANIFESTS += [
     'test/browser/browser.ini',
     'test/browser/creditCard/browser.ini',
+    'test/browser/focus-leak/browser.ini',
 ]
 
 XPCSHELL_TESTS_MANIFESTS += ['test/unit/xpcshell.ini']

browser/extensions/formautofill/test/browser/focus-leak/browser.ini

@@ -0,0 +1,10 @@
+[DEFAULT]
+support-files =
+  doc_iframe_typecontent_input_focus.xul
+  doc_iframe_typecontent_input_focus_frame.html
+  ../head.js
+
+# This test is used to detect a leak.
+# Keep it isolated in a dedicated test folder to make sure the leak is cleaned
+# up as a sideeffect of another test.
+[browser_iframe_typecontent_input_focus.js]

browser/extensions/formautofill/test/browser/focus-leak/browser_iframe_typecontent_input_focus.js

@@ -0,0 +1,55 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const URL_ROOT =
+  "chrome://mochitests/content/browser/browser/extensions/formautofill/test/browser/focus-leak/";
+
+const XUL_FRAME_URI = URL_ROOT + "doc_iframe_typecontent_input_focus.xul";
+const INNER_HTML_FRAME_URI =
+  URL_ROOT + "doc_iframe_typecontent_input_focus_frame.html";
+
+/**
+ * Check that focusing an input in a frame with type=content embedded in a xul
+ * document does not leak.
+ */
+add_task(async function() {
+  const doc = gBrowser.ownerDocument;
+  const linkedBrowser = gBrowser.selectedTab.linkedBrowser;
+  const browserContainer = gBrowser.getBrowserContainer(linkedBrowser);
+
+  info("Load the test page in a frame with type content");
+  const frame = doc.createXULElement("iframe");
+  frame.setAttribute("type", "content");
+  browserContainer.appendChild(frame);
+
+  info("Wait for the xul iframe to be loaded");
+  const onXulFrameLoad = BrowserTestUtils.waitForEvent(frame, "load", true);
+  frame.setAttribute("src", XUL_FRAME_URI);
+  await onXulFrameLoad;
+
+  const panelFrame = frame.contentDocument.querySelector("#html-iframe");
+
+  info("Wait for the html iframe to be loaded");
+  const onFrameLoad = BrowserTestUtils.waitForEvent(panelFrame, "load", true);
+  panelFrame.setAttribute("src", INNER_HTML_FRAME_URI);
+  await onFrameLoad;
+
+  info("Focus an input inside the iframe");
+  const focusMeInput = panelFrame.contentDocument.querySelector(".focusme");
+  const onFocus = BrowserTestUtils.waitForEvent(focusMeInput, "focus");
+  focusMeInput.focus();
+  await onFocus;
+
+  // This assert is not really meaningful, the main purpose of the test is
+  // to check against leaks.
+  is(
+    focusMeInput,
+    panelFrame.contentDocument.activeElement,
+    "The .focusme input is the active element"
+  );
+
+  // Stop the test without blurring the input, the cleanup should still prevent
+  // leaks in the test.
+});

browser/extensions/formautofill/test/browser/focus-leak/doc_iframe_typecontent_input_focus.xul

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        xmlns:html="http://www.w3.org/1999/xhtml">
+  <box>
+    <html:iframe id="html-iframe"/>
+  </box>
+</window>

browser/extensions/formautofill/test/browser/focus-leak/doc_iframe_typecontent_input_focus_frame.html

@@ -0,0 +1,6 @@
+<!DOCTYPE html>
+<html>
+  <body>
+    <input type="text" name="test" class="focusme">
+  </body>
+</html>