Bug 1689445 - make accessible retrieval synchronous. r=Jamie

Differential Revision: https://phabricator.services.mozilla.com/D104126

testing/mochitest/tests/SimpleTest/AccessibilityUtils.js

@@ -14,9 +14,6 @@
  */
 
 this.AccessibilityUtils = (function() {
-  // Duration until the accessible lookup times out.
-  const GET_ACCESSIBLE_TIMEOUT = 1000;
-
   const FORCE_DISABLE_ACCESSIBILITY_PREF = "accessibility.force_disabled";
 
   // Accessible states.
@@ -435,6 +432,32 @@ this.AccessibilityUtils = (function() {
     }
   }
 
+  /**
+   * Walk node ancestry and force refresh driver tick in every document.
+   * @param {DOMNode} node
+   *        Node for traversing the ancestry.
+   */
+  function forceRefreshDriverTick(node) {
+    const wins = [];
+    let bc = BrowsingContext.getFromWindow(node.ownerDocument.defaultView); // eslint-disable-line
+    while (bc) {
+      wins.push(bc.associatedWindow);
+      bc = bc.embedderWindowGlobal?.browsingContext;
+    }
+
+    let win = wins.pop();
+    while (win) {
+      // Stop the refresh driver from doing its regular ticks and force two
+      // refresh driver ticks: first to let layout update and notify a11y,  and
+      // the second to let a11y process updates.
+      win.windowUtils.advanceTimeAndRefresh(100);
+      win.windowUtils.advanceTimeAndRefresh(100);
+      // Go back to normal refresh driver ticks.
+      win.windowUtils.restoreNormalRefresh();
+      win = wins.pop();
+    }
+  }
+
   /**
    * Get an accessible object for a node.
    * Note: this method will not resolve if accessible object does not become
@@ -443,10 +466,10 @@ this.AccessibilityUtils = (function() {
    * @param  {DOMNode} node
    *         Node to get the accessible object for.
    *
-   * @return {Promise.<nsIAccessible>}
-   *         Promise with an accessibility object for a given node.
+   * @return {nsIAccessible}
+   *         Accessibility object for a given node.
    */
-  async function getAccessible(node) {
+  function getAccessible(node) {
     const accessibilityService = Cc[
       "@mozilla.org/accessibilityService;1"
     ].getService(Ci.nsIAccessibilityService);
@@ -460,28 +483,9 @@ this.AccessibilityUtils = (function() {
       return acc;
     }
 
-    let resolver, timeoutID;
-    const accPromise = new Promise(resolve => {
-      resolver = resolve;
-    });
-
-    const observe = subject => {
-      acc = accessibilityService.getAccessibleFor(node);
-      if (acc) {
-        clearTimeout(timeoutID);
-        SpecialPowers.Services.obs.removeObserver(observe, "accessible-event");
-        resolver(acc);
-      }
-    };
-    SpecialPowers.Services.obs.addObserver(observe, "accessible-event");
-
-    timeoutID = setTimeout(() => {
-      // Final attempt in case the show event never fired.
-      SpecialPowers.Services.obs.removeObserver(observe, "accessible-event");
-      resolver(accessibilityService.getAccessibleFor(node));
-    }, GET_ACCESSIBLE_TIMEOUT);
-
-    return accPromise;
+    // Force refresh tick throughout document hierarchy
+    forceRefreshDriverTick(node);
+    return accessibilityService.getAccessibleFor(node);
   }
 
   function runIfA11YChecks(task) {
@@ -498,8 +502,8 @@ this.AccessibilityUtils = (function() {
    *
    */
   const AccessibilityUtils = {
-    async assertCanBeClicked(node) {
-      const acc = await getAccessible(node);
+    assertCanBeClicked(node) {
+      const acc = getAccessible(node);
       if (!acc) {
         if (gEnv.mustHaveAccessibleRule) {
           a11yFail("Node is not accessible via accessibility API", {

testing/mochitest/tests/SimpleTest/EventUtils.js

@@ -227,7 +227,7 @@ function computeButtons(aEvent, utils) {
   return utils.MOUSE_BUTTONS_NOT_SPECIFIED;
 }
 
-async function sendMouseEvent(aEvent, aTarget, aWindow) {
+function sendMouseEvent(aEvent, aTarget, aWindow) {
   if (
     ![
       "click",
@@ -253,7 +253,7 @@ async function sendMouseEvent(aEvent, aTarget, aWindow) {
   }
 
   if (aEvent.type === "click" && this.AccessibilityUtils) {
-    await this.AccessibilityUtils.assertCanBeClicked(aTarget);
+    this.AccessibilityUtils.assertCanBeClicked(aTarget);
   }
 
   var event = aWindow.document.createEvent("MouseEvent");