Bug 2083733. r=arai

void Loader::AddPerformanceEntryForCachedSheet(SheetLoadData& aLoadData) {

  MOZ_ASSERT(aLoadData.mURI);

  if (!aLoadData.mNetworkMetadata) {

  if (!mDocument || !aLoadData.mNetworkMetadata) {

    return;

  }

  if (!mDocument) {

  if (aLoadData.mParentData &&

      !aLoadData.mParentData->mSheet->IsOriginClean()) {

    return;

  }

  nsAutoCString name;

  aLoadData.mURI->GetSpec(name);

  NS_ConvertUTF8toUTF16 entryName(name);

<!DOCTYPE HTML>

<meta charset=utf-8>

<title>Resource timing entries for cached @import children of stylesheets</title>

<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=2083733">

<script src="/resources/testharness.js"></script>

<script src="/resources/testharnessreport.js"></script>

<script src="/common/get-host-info.sub.js"></script>

<script src="/common/utils.js"></script>

<body>

<script>

const {ORIGIN, HTTP_REMOTE_ORIGIN} = get_host_info();

const RESOURCES = "/resource-timing/resources/";

async function loadInFrame(t, href) {

  const iframe = document.createElement("iframe");

  iframe.srcdoc = `<link rel="stylesheet" href="${href}">`;

  await new Promise(resolve => {

    iframe.onload = resolve;

    document.body.appendChild(iframe);

  });

  t.add_cleanup(() => iframe.remove());

  return iframe.contentWindow;

}

// The first load caches the child stylesheet, but not the parent, which is

// no-store, so the second load re-parses the parent and gets the child from

// the cache.

async function loadTwice(t, parentOrigin, childOrigin) {

  const id = token();

  const child = `${childOrigin}${RESOURCES}cacheable-import-child.css?${id}`;

  const parent = v =>

    `${parentOrigin}${RESOURCES}no-store-importer.sub.css?import=${encodeURIComponent(child)}&v=${v}`;

  await loadInFrame(t, parent(1));

  const win = await loadInFrame(t, parent(2));

  await new Promise(resolve => t.step_timeout(resolve, 0));

  assert_equals(win.performance.getEntriesByName(parent(2)).length, 1,

                "Parent stylesheet should be in the timeline");

  return win.performance.getEntriesByName(child).length;

}

promise_test(async t => {

  assert_equals(await loadTwice(t, HTTP_REMOTE_ORIGIN, HTTP_REMOTE_ORIGIN), 0);

}, "Cached @import children of cross-origin stylesheets are not in the timeline");

promise_test(async t => {

  assert_equals(await loadTwice(t, ORIGIN, ORIGIN), 1);

}, "Cached same-origin @import children of same-origin stylesheets are in the timeline");

promise_test(async t => {

  assert_equals(await loadTwice(t, ORIGIN, HTTP_REMOTE_ORIGIN), 1);

}, "Cached cross-origin @import children of same-origin stylesheets are in the timeline");

</script>

</body>

.child { color: blue }

Content-Type: text/css

Cache-Control: max-age=600

@import "{{GET[import]}}";