--- a/testing/web-platform/meta/MANIFEST.json
+++ b/testing/web-platform/meta/MANIFEST.json
@@ -382276,16 +382276,36 @@
      "/xhr/sync-no-progress.any.html",
      {}
     ],
     [
      "/xhr/sync-no-progress.any.worker.html",
      {}
     ]
    ],
+   "xhr/sync-no-timeout.any.js": [
+    [
+     "/xhr/sync-no-timeout.any.html",
+     {
+      "timeout": "long"
+     }
+    ],
+    [
+     "/xhr/sync-no-timeout.any.sharedworker.html",
+     {
+      "timeout": "long"
+     }
+    ],
+    [
+     "/xhr/sync-no-timeout.any.worker.html",
+     {
+      "timeout": "long"
+     }
+    ]
+   ],
    "xhr/template-element.html": [
     [
      "/xhr/template-element.html",
      {}
     ]
    ],
    "xhr/timeout-cors-async.htm": [
     [
@@ -431318,17 +431338,17 @@
    "949851a16fd799f6610bb3e657fa7ab5b7949a90",
    "support"
   ],
   "content-security-policy/generic/policy-does-not-affect-child.sub.html": [
    "7e092f21440fffed98068f59bd2ddfd09a683515",
    "testharness"
   ],
   "content-security-policy/generic/policy-inherited-correctly-by-plznavigate.html": [
-   "11de7fcc2fd1ca6e2277b22a53a2c2c7ba11aa2c",
+   "64d198faf803c12e444cf02f5f0b994e32617923",
    "testharness"
   ],
   "content-security-policy/generic/policy-inherited-correctly-by-plznavigate.html.sub.headers": [
    "0ca17bc3c1370af097fdb2ee803cc802c7e58718",
    "support"
   ],
   "content-security-policy/generic/positiveTest.js": [
    "92b715fcc3269e189318734739a5e4fb620d9dff",
@@ -520138,25 +520158,25 @@
    "71dcc60c4ff59690927c1575fff2eecf85ee558f",
    "reftest"
   ],
   "css/css-scoping/shadow-fallback-dynamic-005.html": [
    "ab3c3d205e59df800ba5b4217245b83685521c31",
    "reftest"
   ],
   "css/css-scoping/shadow-host-with-before-after.html": [
-   "b33e82815776f05b6292a88bbb95daa882a50ac6",
+   "99af6e29e69b3131b59dbdc2b0eead52931123c2",
    "reftest"
   ],
   "css/css-scoping/shadow-reassign-dynamic-001.html": [
    "11ed4da2e6ce88d8a2b98a8f1c814417ef7770dd",
    "reftest"
   ],
   "css/css-scoping/shadow-reassign-dynamic-002.html": [
-   "130734170945e395bab92ac0ce799113d9ab9c96",
+   "2a90e0623a99cfb46430f0236ceea44f93a25131",
    "reftest"
   ],
   "css/css-scoping/shadow-root-insert-into-document.html": [
    "2cee9fff35c9222074f4ef78dcfcb8a3e02bbc98",
    "reftest"
   ],
   "css/css-scoping/slotted-invalidation.html": [
    "c500e1ceba1b293d45df5f66fd89d4a5d9ceb952",
@@ -607298,17 +607318,17 @@
    "ad5ca174b55222c41d1dc1a21fe0bc070357062b",
    "testharness"
   ],
   "service-workers/service-worker/import-scripts-resource-map.https.html": [
    "6bc46467c667f942fd30de063806474e8c94cff0",
    "testharness"
   ],
   "service-workers/service-worker/import-scripts-updated-flag.https.html": [
-   "e902940bec870cf548c576b5fd06d2e71fd3f97a",
+   "16cfa33f95de96bc0a2bc8b1102127f0e4922bd6",
    "testharness"
   ],
   "service-workers/service-worker/indexeddb.https.html": [
    "2211cdead473877e238cc13ed0ccfa8269bfc7cc",
    "testharness"
   ],
   "service-workers/service-worker/install-event-type.https.html": [
    "55175d94a5d90a030c03d598c079455bb93c71c8",
@@ -608146,17 +608166,17 @@
    "9507f4a23a9f54a898139c19e62fdf6ce3b21690",
    "support"
   ],
   "service-workers/service-worker/resources/import-scripts-resource-map-worker.js": [
    "bafc81b044c2a52f4ceefcd15a0b8b3c7553146e",
    "support"
   ],
   "service-workers/service-worker/resources/import-scripts-updated-flag-worker.js": [
-   "b83d48b7ed268293b4788e36bcd7293b1b15e751",
+   "979fca5a705f9794b898e2b3c2c75e7133487ee4",
    "support"
   ],
   "service-workers/service-worker/resources/import-scripts-version.py": [
    "1f508292f99f22a8b4105658ebdb9568d46d2004",
    "support"
   ],
   "service-workers/service-worker/resources/indexeddb-worker.js": [
    "444b05736f532dc37ba3887cd02cf75d40f1706e",
@@ -625661,16 +625681,20 @@
   "xhr/status-error.htm": [
    "42182437d8c1015339825c035127877f4970decb",
    "testharness"
   ],
   "xhr/sync-no-progress.any.js": [
    "db6171c61a37cd98ea5b9c1549432f1e2b53e7eb",
    "testharness"
   ],
+  "xhr/sync-no-timeout.any.js": [
+   "d1078052ef5593c33de085f9e0c5ceb73c47f02e",
+   "testharness"
+  ],
   "xhr/template-element.html": [
    "748f12beaa646e244f8312afd545f56075cac727",
    "testharness"
   ],
   "xhr/timeout-cors-async.htm": [
    "d5b0fa4ab0907d58f7cf5796c2bb740e5f91a82f",
    "testharness"
   ],

new file mode 100644
--- /dev/null
+++ b/testing/web-platform/tests/xhr/sync-no-timeout.any.js
@@ -0,0 +1,16 @@
+// META: global=sharedworker
+// META: timeout=long
+
+// This is a regression test for https://crbug.com/844268, when a timeout of 10
+// seconds was applied to XHR in Chrome. There should be no timeout unless the
+// "timeout" parameter is set on the object.
+test(t => {
+  let xhr = new XMLHttpRequest();
+
+  // For practical reasons, we can't wait forever. 12 seconds is long enough to
+  // reliably reproduce the bug in Chrome.
+  xhr.open('GET', 'resources/trickle.py?ms=1000&count=12', false);
+
+  // The test will fail if this throws.
+  xhr.send();
+}, 'Sync XHR should not have a timeout');