tor-browser

The Tor Browser
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test_bug1756118.html (3209B)

      1 <!DOCTYPE HTML>
      2 <html>
      3 <!--
      4 https://bugzilla.mozilla.org/show_bug.cgi?id=1756118
      5 -->
      6 <head>
      7  <meta charset="utf-8">
      8  <title>Test for Bug 1756118: A removed ResizeObserver shouldn't keep the refresh driver ticking</title>
      9  <script src="/tests/SimpleTest/SimpleTest.js"></script>
     10  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
     11 </head>
     12 <body onload="run()">
     13 <a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1756118">Mozilla Bug 1756118</a>
     14 <div id="display">
     15  <div id="resizeMe"></div>
     16 </div>
     17 <pre id="test">
     18 <script>
     19 "use strict";
     20 SimpleTest.waitForExplicitFinish();
     21 SimpleTest.requestFlakyTimeout("need to allow time to pass so that we can " +
     22                               "detect unwanted extra refresh driver ticks");
     23 const gUtils = SpecialPowers.getDOMWindowUtils(window);
     24 
     25 async function addAndRemoveResizeObserver(shouldResizeTarget) {
     26  // Register a resize observer:
     27  let ro = new ResizeObserver(function() { info("ResizeObserver callback"); });
     28  ro.observe(resizeMe);
     29 
     30  // double-rAF to flush pending paints:
     31  await new Promise(r => requestAnimationFrame(r));
     32  await new Promise(r => requestAnimationFrame(r));
     33 
     34  ok(gUtils.refreshDriverHasPendingTick,
     35     "Expecting refresh driver to be ticking, with ResizeObserver registered");
     36 
     37  // Unregister resize observer:
     38  ro.unobserve(resizeMe);
     39 
     40  // double-rAF to flush pending paints:
     41  await new Promise(r => requestAnimationFrame(r));
     42  await new Promise(r => requestAnimationFrame(r));
     43 
     44  // ...and importantly: make one additional change to the document.
     45  // This causes a refresh driver tick, which in buggy builds causes
     46  // the refresh driver to keep ticking indefinitely.  (In buggy builds, this
     47  // bonus tick notifies our ResizeObserverController, and it never unregisters
     48  // and hence keeps the refresh driver ticking from that point on.)
     49  resizeMe.style.height = "100px";
     50 }
     51 
     52 async function expectTicksToStop() {
     53  let didStopTicking = false;
     54  // Note: The maximum loop count here is an arbitrary large value, just to let
     55  // us gracefully handle edge cases where multiple setTimeouts resolve before
     56  // a pending refresh driver tick.  Really, we just want to be sure the refresh
     57  // driver *eventually* stops ticking, and we can do so gracefully by polling
     58  // with some generous-but-finite number of checks here.
     59  for (var i = 0; i < 100; i++) {
     60    await new Promise(r => setTimeout(r, 8));
     61    if(!gUtils.refreshDriverHasPendingTick) {
     62      didStopTicking = true;
     63      break;
     64    }
     65  }
     66  ok(didStopTicking, "refresh driver should have eventually stopped ticking");
     67 }
     68 
     69 async function run() {
     70  // By default, the refresh driver ticks on its own for some period of time
     71  // after pageload.  Turn that off so we don't have to wait it out:
     72  await SpecialPowers.pushPrefEnv({'set':
     73                                   [['layout.keep_ticking_after_load_ms', 0]]});
     74 
     75  // Start out with a double-rAF, to flush paints from pageload:
     76  await new Promise(r => requestAnimationFrame(r));
     77  await new Promise(r => requestAnimationFrame(r));
     78 
     79  await addAndRemoveResizeObserver(true);
     80  await expectTicksToStop();
     81 
     82  SimpleTest.finish();
     83 }
     84 </script>
     85 </pre>
     86 </body>
     87 </html>