Filed by: ncsoregi [at] mozilla.com
Parsed log: https://treeherder.mozilla.org/logviewer.html#?job_id=264538889&repo=mozilla-inbound
Full log: https://queue.taskcluster.net/v1/task/JqpEJIFNQ6q33hS78ATH9g/runs/0/artifacts/public/logs/live_backing.log

entering test:
[task 2019-09-02T11:09:02.041Z] 11:09:02 INFO - TEST-START | Shutdown
[task 2019-09-02T11:09:02.041Z] 11:09:02 INFO - Browser Chrome Test Summary
[task 2019-09-02T11:09:02.041Z] 11:09:02 INFO - Passed: 744
[task 2019-09-02T11:09:02.041Z] 11:09:02 INFO - Failed: 0
[task 2019-09-02T11:09:02.041Z] 11:09:02 INFO - Todo: 0
[task 2019-09-02T11:09:02.041Z] 11:09:02 INFO - Mode: e10s
[task 2019-09-02T11:09:02.042Z] 11:09:02 INFO - *** End BrowserChrome Test Results ***

[task 2019-09-02T11:09:04.208Z] 11:09:04 INFO - GECKO(5228) | --DOMWINDOW == 0 (000001975349C400) [pid = 4864] [serial = 14] [outer = 0000000000000000] [url = resource://gre-resources/hiddenWindow.html]
[task 2019-09-02T11:09:04.298Z] 11:09:04 INFO - GECKO(5228) | [Parent 4864, Main Thread] WARNING: XPCOM objects created/destroyed from static ctor/dtor: file z:/build/build/src/xpcom/base/nsTraceRefcnt.cpp, line 198
[task 2019-09-02T11:09:04.298Z] 11:09:04 INFO - GECKO(5228) | [Parent 4864, Main Thread] WARNING: XPCOM objects created/destroyed from static ctor/dtor: file z:/build/build/src/xpcom/base/nsTraceRefcnt.cpp, line 198
[task 2019-09-02T11:09:04.298Z] 11:09:04 INFO - GECKO(5228) | nsStringStats
[task 2019-09-02T11:09:04.298Z] 11:09:04 INFO - GECKO(5228) | => mAllocCount: 298376
[task 2019-09-02T11:09:04.298Z] 11:09:04 INFO - GECKO(5228) | => mReallocCount: 2
[task 2019-09-02T11:09:04.298Z] 11:09:04 INFO - GECKO(5228) | => mFreeCount: 298376
[task 2019-09-02T11:09:04.299Z] 11:09:04 INFO - GECKO(5228) | => mShareCount: 364560
[task 2019-09-02T11:09:04.299Z] 11:09:04 INFO - GECKO(5228) | => mAdoptCount: 5668
[task 2019-09-02T11:09:04.299Z] 11:09:04 INFO - GECKO(5228) | => mAdoptFreeCount: 6106
[task 2019-09-02T11:09:04.299Z] 11:09:04 INFO - GECKO(5228) | => Process ID: 4864, Thread ID: 3316
[task 2019-09-02T11:09:04.323Z] 11:09:04 INFO - TEST-INFO | Main app process: exit 0
[task 2019-09-02T11:09:04.323Z] 11:09:04 ERROR - TEST-UNEXPECTED-FAIL | toolkit/components/extensions/test/browser/browser_ext_themes_ntp_colors_perwindow.js | leaked 1 window(s) until shutdown [url = chrome://browser/content/browser.xhtml]
[task 2019-09-02T11:09:04.324Z] 11:09:04 ERROR - TEST-UNEXPECTED-FAIL | toolkit/components/extensions/test/browser/browser_ext_themes_ntp_colors_perwindow.js | leaked 1 window(s) until shutdown [url = about:blank]
[task 2019-09-02T11:09:04.324Z] 11:09:04 INFO - TEST-INFO | toolkit/components/extensions/test/browser/browser_ext_themes_ntp_colors_perwindow.js | windows(s) leaked: [pid = 4864] [serial = 62], [pid = 4864] [serial = 63]