Bug: Intermittent browser/components/sessionstore/test/browser_scrollPositions.js | no scroll stored - Got "{\"children\":[{\"scroll\":\"100,315\"},null]}", expected "null"
Status: RESOLVED
Priority: P5
Resolution: DUPLICATE
Created: 2021-03-29 17:42:09+00:00
Resolved: 2022-07-27 17:35:13+00:00

**Filed by:** malexandru [at] mozilla.com
**Parsed log:** https://treeherder.mozilla.org/logviewer?job_id=334793131&repo=autoland
**Full log:** https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/FJz7uxlKSPSIeupbM8Gwnw/runs/1/artifacts/public/logs/live_backing.log

---
```
[task 2021-03-29T16:48:45.014Z] 16:48:45     INFO - TEST-OK | browser/components/sessionstore/test/browser_revive_crashed_bg_tabs.js | took 1366ms
[task 2021-03-29T16:48:45.034Z] 16:48:45     INFO - GECKO(1532) | [Child 2303: Main Thread]: I/DocShellAndDOMWindowLeak ++DOCSHELL 7fc6a8f07000 == 3 [pid = 2303] [id = 92]
[task 2021-03-29T16:48:45.034Z] 16:48:45     INFO - GECKO(1532) | [Child 2303: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 10 (7fc6ab29c740) [pid = 2303] [serial = 245] [outer = 0]
[task 2021-03-29T16:48:45.035Z] 16:48:45     INFO - GECKO(1532) | [Child 2303: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 11 (7fc6a8f09800) [pid = 2303] [serial = 246] [outer = 7fc6ab29c740]
[task 2021-03-29T16:48:45.070Z] 16:48:45     INFO - checking window state
[task 2021-03-29T16:48:45.102Z] 16:48:45     INFO - TEST-START | browser/components/sessionstore/test/browser_scrollPositions.js
[task 2021-03-29T16:48:45.158Z] 16:48:45     INFO - GECKO(1532) | [Child 2212: Main Thread]: I/DocShellAndDOMWindowLeak ++DOCSHELL 7f15e32f2800 == 6 [pid = 2212] [id = 157]
[task 2021-03-29T16:48:45.159Z] 16:48:45     INFO - GECKO(1532) | [Child 2212: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 18 (7f15e4009040) [pid = 2212] [serial = 407] [outer = 0]
[task 2021-03-29T16:48:45.160Z] 16:48:45     INFO - GECKO(1532) | [Child 2212: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 19 (7f15e32f6c00) [pid = 2212] [serial = 408] [outer = 7f15e4009040]
[task 2021-03-29T16:48:45.279Z] 16:48:45     INFO - GECKO(1532) | [Child 2212: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 20 (7f15e372a800) [pid = 2212] [serial = 409] [outer = 7f15e4009040]
[task 2021-03-29T16:48:45.570Z] 16:48:45     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 249 (7f17488a4900) [pid = 1532] [serial = 899] [outer = 0] [url = chrome://browser/content/browser.xhtml]
[task 2021-03-29T16:48:45.581Z] 16:48:45     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 248 (7f172b35ac80) [pid = 1532] [serial = 845] [outer = 0] [url = about:welcomeback]
[task 2021-03-29T16:48:45.581Z] 16:48:45     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 247 (7f1730bb83c0) [pid = 1532] [serial = 858] [outer = 0] [url = about:sessionrestore]
[task 2021-03-29T16:48:45.581Z] 16:48:45     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 246 (7f172b35ae40) [pid = 1532] [serial = 852] [outer = 0] [url = about:welcomeback]
[task 2021-03-29T16:48:45.581Z] 16:48:45     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 245 (7f1703f1bc80) [pid = 1532] [serial = 979] [outer = 0] [url = about:config]
[task 2021-03-29T16:48:45.581Z] 16:48:45     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 244 (7f1703d5e740) [pid = 1532] [serial = 976] [outer = 0] [url = about:config]
[task 2021-03-29T16:48:45.581Z] 16:48:45     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 243 (7f1703d5ee40) [pid = 1532] [serial = 973] [outer = 0] [url = about:config]
[task 2021-03-29T16:48:45.581Z] 16:48:45     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 242 (7f1703f1b740) [pid = 1532] [serial = 968] [outer = 0] [url = about:blank]
[task 2021-03-29T16:48:45.581Z] 16:48:45     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 241 (7f170318a580) [pid = 1532] [serial = 963] [outer = 0] [url = about:blank]
[task 2021-03-29T16:48:45.584Z] 16:48:45     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 240 (7f170a632200) [pid = 1532] [serial = 958] [outer = 0] [url = about:blank]
[task 2021-03-29T16:48:45.585Z] 16:48:45     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 239 (7f171a519ac0) [pid = 1532] [serial = 953] [outer = 0] [url = about:blank]
[task 2021-03-29T16:48:45.585Z] 16:48:45     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 238 (7f17289f6ac0) [pid = 1532] [serial = 948] [outer = 0] [url = about:blank]
[task 2021-03-29T16:48:45.705Z] 16:48:45     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 1 (7f91cbf6f400) [pid = 2340] [serial = 63] [outer = 0] [url = https://example.com/browser/browser/components/sessionstore/test/empty.html]
[task 2021-03-29T16:48:45.706Z] 16:48:45     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 0 (7f91c5eb9400) [pid = 2340] [serial = 65] [outer = 0] [url = about:blank]
[task 2021-03-29T16:48:45.726Z] 16:48:45     INFO - GECKO(1532) | [Child 2373: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 1 (7f1ec9706800) [pid = 2373] [serial = 38] [outer = 0] [url = https://example.com/browser/browser/components/sessionstore/test/empty.html]
[task 2021-03-29T16:48:45.726Z] 16:48:45     INFO - GECKO(1532) | [Child 2373: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 0 (7f1ec35c4000) [pid = 2373] [serial = 40] [outer = 0] [url = about:blank]
[task 2021-03-29T16:48:45.854Z] 16:48:45     INFO - GECKO(1532) | [Child 2412: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 1 (7fc953420040) [pid = 2412] [serial = 16] [outer = 0] [url = https://example.org/browser/browser/components/sessionstore/test/empty.html]
[task 2021-03-29T16:48:45.975Z] 16:48:45     INFO - GECKO(1532) | [Child 2403: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 1 (7f624e563ac0) [pid = 2403] [serial = 16] [outer = 0] [url = https://example.org/browser/browser/components/sessionstore/test/empty.html]
[task 2021-03-29T16:48:46.030Z] 16:48:46     INFO - GECKO(1532) | [Child 2400: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 1 (7ff9ec045040) [pid = 2400] [serial = 18] [outer = 0] [url = https://example.org/browser/browser/components/sessionstore/test/empty.html]
[task 2021-03-29T16:48:46.309Z] 16:48:46     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak ++DOCSHELL 7f91c5eb7800 == 1 [pid = 2340] [id = 27]
[task 2021-03-29T16:48:46.309Z] 16:48:46     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 1 (7f91c4d0d200) [pid = 2340] [serial = 66] [outer = 0]
[task 2021-03-29T16:48:46.312Z] 16:48:46     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 2 (7f91c5eb8c00) [pid = 2340] [serial = 67] [outer = 7f91c4d0d200]
[task 2021-03-29T16:48:46.501Z] 16:48:46     INFO - GECKO(1532) | [Child 2340, Main Thread] WARNING: NS_ENSURE_TRUE(info) failed: file /builds/worker/checkouts/gecko/extensions/permissions/PermissionDelegateHandler.cpp:348
<...>
[task 2021-03-29T16:49:19.849Z] 16:49:19     INFO - TEST-PASS | browser/components/sessionstore/test/browser_scrollPositions.js | scroll is fine - 
[task 2021-03-29T16:49:19.850Z] 16:49:19     INFO - Console message: [JavaScript Error: "1617036550761	addons.xpi	ERROR	System addon update list error Error: got node name: html, expected: updates" {file: "resource://gre/modules/Log.jsm" line: 723}]
[task 2021-03-29T16:49:19.851Z] 16:49:19     INFO - append@resource://gre/modules/Log.jsm:723:12
[task 2021-03-29T16:49:19.851Z] 16:49:19     INFO - log@resource://gre/modules/Log.jsm:379:16
[task 2021-03-29T16:49:19.851Z] 16:49:19     INFO - error@resource://gre/modules/Log.jsm:387:10
[task 2021-03-29T16:49:19.852Z] 16:49:19     INFO - updateSystemAddons/res<@resource://gre/modules/addons/XPIInstall.jsm:4016:25
[task 2021-03-29T16:49:19.852Z] 16:49:19     INFO - 
[task 2021-03-29T16:49:19.853Z] 16:49:19     INFO - Buffered messages finished
[task 2021-03-29T16:49:19.854Z] 16:49:19     INFO - TEST-UNEXPECTED-FAIL | browser/components/sessionstore/test/browser_scrollPositions.js | no scroll stored - Got "{\"children\":[{\"scroll\":\"100,315\"},null]}", expected "null"
[task 2021-03-29T16:49:19.854Z] 16:49:19     INFO - Stack trace:
[task 2021-03-29T16:49:19.854Z] 16:49:19     INFO - chrome://mochikit/content/browser-test.js:test_is:1359
[task 2021-03-29T16:49:19.855Z] 16:49:19     INFO - chrome://mochitests/content/browser/browser/components/sessionstore/test/head.js:checkScroll:623
[task 2021-03-29T16:49:19.855Z] 16:49:19     INFO - GECKO(1532) | [Child 2212: Main Thread]: I/DocShellAndDOMWindowLeak --DOCSHELL 7f15e37ee400 == 2 [pid = 2212] [id = 159] [url = http://example.com/browser/browser/components/sessionstore/test/browser_scrollPositions_sample.html]
[task 2021-03-29T16:49:19.856Z] 16:49:19     INFO - GECKO(1532) | [Child 2212: Main Thread]: I/DocShellAndDOMWindowLeak --DOCSHELL 7f15e37f0800 == 1 [pid = 2212] [id = 160] [url = http://example.com/browser/browser/components/sessionstore/test/browser_scrollPositions_sample.html]
[task 2021-03-29T16:49:19.856Z] 16:49:19     INFO - Leaving test bound test_scroll_nested
[task 2021-03-29T16:49:19.857Z] 16:49:19     INFO - Entering test bound test_scroll_background_tabs
[task 2021-03-29T16:49:19.858Z] 16:49:19     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak ++DOCSHELL 7f16ffecdc00 == 6 [pid = 1532] [id = 422]
[task 2021-03-29T16:49:19.858Z] 16:49:19     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 11 (7f170318a040) [pid = 1532] [serial = 1031] [outer = 0]
[task 2021-03-29T16:49:19.859Z] 16:49:19     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 12 (7f16ffecf400) [pid = 1532] [serial = 1032] [outer = 7f170318a040]
[task 2021-03-29T16:49:19.859Z] 16:49:19     INFO - GECKO(1532) | [Parent 1532, Main Thread] WARNING: NS_ENSURE_TRUE(uri) failed: file /builds/worker/checkouts/gecko/caps/BasePrincipal.cpp:1327
[task 2021-03-29T16:49:19.860Z] 16:49:19     INFO - GECKO(1532) | [Parent 1532, Main Thread] WARNING: NS_ENSURE_TRUE(rootFrame) failed: file /builds/worker/checkouts/gecko/dom/base/nsGlobalWindowOuter.cpp:4250
[task 2021-03-29T16:49:19.937Z] 16:49:19     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak ++DOCSHELL 7f1700598000 == 7 [pid = 1532] [id = 423]
[task 2021-03-29T16:49:19.938Z] 16:49:19     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 13 (7f170318a580) [pid = 1532] [serial = 1033] [outer = 0]
[task 2021-03-29T16:49:19.986Z] 16:49:19     INFO - GECKO(1532) | [Child 2212: Main Thread]: I/DocShellAndDOMWindowLeak ++DOCSHELL 7f15e32ec800 == 2 [pid = 2212] [id = 161]
[task 2021-03-29T16:49:19.988Z] 16:49:19     INFO - GECKO(1532) | [Child 2212: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 7 (7f15e32d8200) [pid = 2212] [serial = 417] [outer = 0]
[task 2021-03-29T16:49:19.989Z] 16:49:19     INFO - GECKO(1532) | [Child 2212: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 8 (7f15e32ee000) [pid = 2212] [serial = 418] [outer = 7f15e32d8200]
[task 2021-03-29T16:49:20.064Z] 16:49:20     INFO - GECKO(1532) | [Parent 1532, Main Thread] WARNING: NS_ENSURE_TRUE(presShell) failed: file /builds/worker/checkouts/gecko/dom/base/nsGlobalWindowOuter.cpp:4248
[task 2021-03-29T16:49:20.064Z] 16:49:20     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 14 (7f16ffeda400) [pid = 1532] [serial = 1034] [outer = 7f170318a580]
[task 2021-03-29T16:49:20.291Z] 16:49:20     INFO - GECKO(1532) | [Child 2212: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 9 (7f15e32f4000) [pid = 2212] [serial = 419] [outer = 7f15e32d8200]
[task 2021-03-29T16:49:20.367Z] 16:49:20     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak ++DOCSHELL 7f91c4d9cc00 == 4 [pid = 2340] [id = 31]
[task 2021-03-29T16:49:20.368Z] 16:49:20     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 8 (7f91c4d0d900) [pid = 2340] [serial = 78] [outer = 0]
[task 2021-03-29T16:49:20.368Z] 16:49:20     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 9 (7f91c4da0400) [pid = 2340] [serial = 79] [outer = 7f91c4d0d900]
[task 2021-03-29T16:49:20.425Z] 16:49:20     INFO - GECKO(1532) | [Child 2019: Main Thread]: I/DocShellAndDOMWindowLeak ++DOCSHELL 7f24545e3000 == 2 [pid = 2019] [id = 42]
[task 2021-03-29T16:49:20.426Z] 16:49:20     INFO - GECKO(1532) | [Child 2019: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 3 (7f2454df5200) [pid = 2019] [serial = 117] [outer = 0]
[task 2021-03-29T16:49:20.426Z] 16:49:20     INFO - GECKO(1532) | [Child 2019: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 4 (7f24545e4000) [pid = 2019] [serial = 118] [outer = 7f2454df5200]
[task 2021-03-29T16:49:20.503Z] 16:49:20     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 10 (7f91c4da6000) [pid = 2340] [serial = 80] [outer = 7f91c4d0d900]
[task 2021-03-29T16:49:20.538Z] 16:49:20     INFO - GECKO(1532) | [Child 2019: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 5 (7f24545eec00) [pid = 2019] [serial = 119] [outer = 7f2454df5200]
[task 2021-03-29T16:49:20.976Z] 16:49:20     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak --DOCSHELL 7f91cc0b6c00 == 3 [pid = 2340] [id = 29] [url = http://example.com/browser/browser/components/sessionstore/test/browser_scrollPositions_sample.html]
[task 2021-03-29T16:49:20.977Z] 16:49:20     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak --DOCSHELL 7f91cc0b7800 == 2 [pid = 2340] [id = 30] [url = http://example.com/browser/browser/components/sessionstore/test/browser_scrollPositions_sample.html]
[task 2021-03-29T16:49:21.093Z] 16:49:21     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 9 (7f91c5eb8800) [pid = 2340] [serial = 72] [outer = 0] [url = about:blank]
[task 2021-03-29T16:49:21.093Z] 16:49:21     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak --DOCSHELL 7f91c5eb7400 == 1 [pid = 2340] [id = 28] [url = http://example.com/browser/browser/components/sessionstore/test/browser_scrollPositions_sample_frameset.html]
[task 2021-03-29T16:49:21.149Z] 16:49:21     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 8 (7f91c4d0d740) [pid = 2340] [serial = 75] [outer = 0] [url = http://example.com/browser/browser/components/sessionstore/test/browser_scrollPositions_sample.html]
[task 2021-03-29T16:49:21.150Z] 16:49:21     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 7 (7f91c4d0d580) [pid = 2340] [serial = 74] [outer = 0] [url = http://example.com/browser/browser/components/sessionstore/test/browser_scrollPositions_sample.html]
[task 2021-03-29T16:49:21.150Z] 16:49:21     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 6 (7f91c4d0d200) [pid = 2340] [serial = 71] [outer = 0] [url = http://example.com/browser/browser/components/sessionstore/test/browser_scrollPositions_sample_frameset.html]
[task 2021-03-29T16:49:21.532Z] 16:49:21     INFO - TEST-PASS | browser/components/sessionstore/test/browser_scrollPositions.js | scroll on first page is fine - 
[task 2021-03-29T16:49:21.572Z] 16:49:21     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 7 (7f91c4da3400) [pid = 2340] [serial = 81] [outer = 7f91c4d0d900]
[task 2021-03-29T16:49:22.595Z] 16:49:22     INFO - TEST-PASS | browser/components/sessionstore/test/browser_scrollPositions.js | scroll on second page is fine - 
[task 2021-03-29T16:49:22.611Z] 16:49:22     INFO - GECKO(1532) | [Child 2019, Main Thread] WARNING: NS_ENSURE_SUCCESS(rv, rv) failed with result 0x80040111 (NS_ERROR_NOT_AVAILABLE): file /builds/worker/checkouts/gecko/caps/BasePrincipal.cpp:1349
[task 2021-03-29T16:49:22.691Z] 16:49:22     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak ++DOCSHELL 7f170041f800 == 8 [pid = 1532] [id = 424]
[task 2021-03-29T16:49:22.692Z] 16:49:22     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 15 (7f170318a740) [pid = 1532] [serial = 1035] [outer = 0]
[task 2021-03-29T16:49:22.693Z] 16:49:22     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 16 (7f1700423000) [pid = 1532] [serial = 1036] [outer = 7f170318a740]
[task 2021-03-29T16:49:22.721Z] 16:49:22     INFO - GECKO(1532) | [Parent 1532, Main Thread] WARNING: NS_ENSURE_TRUE(rootFrame) failed: file /builds/worker/checkouts/gecko/dom/base/nsGlobalWindowOuter.cpp:4250
[task 2021-03-29T16:49:22.882Z] 16:49:22     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak ++DOCSHELL 7f1702e20800 == 9 [pid = 1532] [id = 425]
[task 2021-03-29T16:49:22.883Z] 16:49:22     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 17 (7f170318ac80) [pid = 1532] [serial = 1037] [outer = 0]
[task 2021-03-29T16:49:22.934Z] 16:49:22     INFO - GECKO(1532) | [Child 2212: Main Thread]: I/DocShellAndDOMWindowLeak ++DOCSHELL 7f15e32eec00 == 3 [pid = 2212] [id = 162]
[task 2021-03-29T16:49:22.934Z] 16:49:22     INFO - GECKO(1532) | [Child 2212: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 10 (7f15e32d8580) [pid = 2212] [serial = 420] [outer = 0]
[task 2021-03-29T16:49:22.934Z] 16:49:22     INFO - GECKO(1532) | [Child 2212: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 11 (7f15e32f0000) [pid = 2212] [serial = 421] [outer = 7f15e32d8580]
[task 2021-03-29T16:49:22.994Z] 16:49:22     INFO - GECKO(1532) | [Parent 1532, Main Thread] WARNING: NS_ENSURE_TRUE(presShell) failed: file /builds/worker/checkouts/gecko/dom/base/nsGlobalWindowOuter.cpp:4248
[task 2021-03-29T16:49:23.002Z] 16:49:23     INFO - GECKO(1532) | [Parent 1532: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 18 (7f1700421c00) [pid = 1532] [serial = 1038] [outer = 7f170318ac80]
[task 2021-03-29T16:49:23.261Z] 16:49:23     INFO - TEST-PASS | browser/components/sessionstore/test/browser_scrollPositions.js | There should be two tabs - 
[task 2021-03-29T16:49:23.262Z] 16:49:23     INFO - TEST-PASS | browser/components/sessionstore/test/browser_scrollPositions.js | Tab should be pending - 
[task 2021-03-29T16:49:23.262Z] 16:49:23     INFO - GECKO(1532) | console.log: [bug 1345098] Lazy browser prematurely inserted via 'messageManager' property access:
[task 2021-03-29T16:49:23.262Z] 16:49:23     INFO - GECKO(1532) | getter@chrome://browser/content/tabbrowser.js:2289:39
[task 2021-03-29T16:49:23.268Z] 16:49:23     INFO - GECKO(1532) | flush@resource:///modules/sessionstore/TabStateFlusher.jsm:123:14
[task 2021-03-29T16:49:23.269Z] 16:49:23     INFO - GECKO(1532) | flush@resource:///modules/sessionstore/TabStateFlusher.jsm:29:36
[task 2021-03-29T16:49:23.269Z] 16:49:23     INFO - GECKO(1532) | test_scroll_background_tabs@chrome://mochitests/content/browser/browser/components/sessionstore/test/browser_scrollPositions.js:215:25
[task 2021-03-29T16:49:23.269Z] 16:49:23     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak ++DOCSHELL 7f91c4da0c00 == 2 [pid = 2340] [id = 32]
[task 2021-03-29T16:49:23.270Z] 16:49:23     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 8 (7f91c4d0d200) [pid = 2340] [serial = 82] [outer = 0]
[task 2021-03-29T16:49:23.270Z] 16:49:23     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 9 (7f91c4da4800) [pid = 2340] [serial = 83] [outer = 7f91c4d0d200]
[task 2021-03-29T16:49:23.334Z] 16:49:23     INFO - GECKO(1532) | [Child 2212: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 12 (7f15e32f6c00) [pid = 2212] [serial = 422] [outer = 7f15e32d8580]
[task 2021-03-29T16:49:23.499Z] 16:49:23     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 10 (7f91c4dab800) [pid = 2340] [serial = 84] [outer = 7f91c4d0d200]
[task 2021-03-29T16:49:23.636Z] 16:49:23     INFO - TEST-PASS | browser/components/sessionstore/test/browser_scrollPositions.js | scroll is still fine - 
[task 2021-03-29T16:49:23.636Z] 16:49:23     INFO - TEST-PASS | browser/components/sessionstore/test/browser_scrollPositions.js | can go back - 
[task 2021-03-29T16:49:23.672Z] 16:49:23     INFO - GECKO(1532) | [Child 2340: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 11 (7f91c4da8c00) [pid = 2340] [serial = 85] [outer = 7f91c4d0d200]
[task 2021-03-29T16:49:23.861Z] 16:49:23     INFO - GECKO(1532) | [Child 2019: Main Thread]: I/DocShellAndDOMWindowLeak ++DOCSHELL 7f24545e6000 == 3 [pid = 2019] [id = 43]
[task 2021-03-29T16:49:23.862Z] 16:49:23     INFO - GECKO(1532) | [Child 2019: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 6 (7f2454df53c0) [pid = 2019] [serial = 120] [outer = 0]
[task 2021-03-29T16:49:23.862Z] 16:49:23     INFO - GECKO(1532) | [Child 2019: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 7 (7f24545e9400) [pid = 2019] [serial = 121] [outer = 7f2454df53c0]
[task 2021-03-29T16:49:23.897Z] 16:49:23     INFO - TEST-PASS | browser/components/sessionstore/test/browser_scrollPositions.js | scroll is still fine after navigating back - 
[task 2021-03-29T16:49:23.963Z] 16:49:23     INFO - GECKO(1532) | [Parent 1532, Main Thread] WARNING: WebProgress Ignored: BrowsingContext is null or discarded: file /builds/worker/checkouts/gecko/dom/ipc/BrowserParent.cpp:2860
[task 2021-03-29T16:49:24.007Z] 16:49:24     INFO - Leaving test bound test_scroll_background_tabs
[task 2021-03-29T16:49:24.028Z] 16:49:24     INFO - GECKO(1532) | MEMORY STAT | vsize 11790MB | residentFast 507MB | heapAllocated 145MB
[task 2021-03-29T16:49:24.028Z] 16:49:24     INFO - TEST-OK | browser/components/sessionstore/test/browser_scrollPositions.js | took 38928ms
[task 2021-03-29T16:49:24.048Z] 16:49:24     INFO - GECKO(1532) | [Child 2212: Main Thread]: I/DocShellAndDOMWindowLeak ++DOCSHELL 7f15e32f0800 == 4 [pid = 2212] [id = 163]
[task 2021-03-29T16:49:24.049Z] 16:49:24     INFO - GECKO(1532) | [Child 2212: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 13 (7f15e32d8900) [pid = 2212] [serial = 423] [outer = 0]
[task 2021-03-29T16:49:24.049Z] 16:49:24     INFO - GECKO(1532) | [Child 2212: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 14 (7f15e32f3400) [pid = 2212] [serial = 424] [outer = 7f15e32d8900]
[task 2021-03-29T16:49:24.117Z] 16:49:24     INFO - checking window state
[task 2021-03-29T16:49:24.174Z] 16:49:24     INFO - TEST-START | browser/components/sessionstore/test/browser_scrollPositionsReaderMode.js```