Filed by: nerli [at] mozilla.com
Parsed log: https://treeherder.mozilla.org/logviewer?job_id=359960583&repo=autoland
Full log: https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/JBTo1CvCQlWvVu9IhTFEAA/runs/0/artifacts/public/logs/live_backing.log
Reftest URL: https://hg.mozilla.org/mozilla-central/raw-file/tip/layout/tools/reftest/reftest-analyzer.xhtml#logurl=https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/JBTo1CvCQlWvVu9IhTFEAA/runs/0/artifacts/public/logs/live_backing.log&only_show_unexpected=1

[task 2021-12-02T11:24:59.704Z] 11:24:59     INFO - TEST-START | netwerk/test/browser/browser_103_telemetry.js
[task 2021-12-02T11:24:59.861Z] 11:24:59     INFO - GECKO(1570) | JavaScript error: http://example.com/browser/netwerk/test/browser/103_preload.html, line 13: TypeError: window.parent.ok is not a function
[task 2021-12-02T11:25:00.050Z] 11:25:00     INFO - TEST-INFO | started process screentopng
[task 2021-12-02T11:25:00.809Z] 11:25:00     INFO - TEST-INFO | screentopng: exit 0
[task 2021-12-02T11:25:00.809Z] 11:25:00     INFO - Buffered messages logged at 11:24:59
[task 2021-12-02T11:25:00.810Z] 11:25:00     INFO - Entering test bound 
[task 2021-12-02T11:25:00.810Z] 11:25:00     INFO - Console message: [JavaScript Error: "The character encoding of the HTML document was not declared. The document will render with garbled text in some browser configurations if the document contains characters from outside the US-ASCII range. The character encoding of the page must be declared in the document or in the transfer protocol." {file: "http://example.com/browser/netwerk/test/browser/103_preload.html" line: 0}]
[task 2021-12-02T11:25:00.810Z] 11:25:00     INFO - Console message: [JavaScript Error: "TypeError: window.parent.ok is not a function" {file: "http://example.com/browser/netwerk/test/browser/103_preload.html" line: 13}]
[task 2021-12-02T11:25:00.812Z] 11:25:00     INFO - checkNumberOfLoads@http://example.com/browser/netwerk/test/browser/103_preload.html:13:17
[task 2021-12-02T11:25:00.812Z] 11:25:00     INFO - @http://example.com/browser/netwerk/test/browser/103_preload.html:19:21
[task 2021-12-02T11:25:00.812Z] 11:25:00     INFO - 
[task 2021-12-02T11:25:00.813Z] 11:25:00     INFO - Buffered messages finished
[task 2021-12-02T11:25:00.814Z] 11:25:00     INFO - TEST-UNEXPECTED-FAIL | netwerk/test/browser/browser_103_telemetry.js | unexpected counts should be zero for EH_NUM_OF_HINTS_PER_PAGE at index 0 - 1 == 0 - JS frame :: resource://testing-common/TelemetryTestUtils.jsm :: assertHistogram :: line 302
[task 2021-12-02T11:25:00.814Z] 11:25:00     INFO - Stack trace:
[task 2021-12-02T11:25:00.814Z] 11:25:00     INFO - resource://testing-common/TelemetryTestUtils.jsm:assertHistogram:302
[task 2021-12-02T11:25:00.815Z] 11:25:00     INFO - chrome://mochitests/content/browser/netwerk/test/browser/browser_103_telemetry.js:null:33
[task 2021-12-02T11:25:00.815Z] 11:25:00     INFO - Not taking screenshot here: see the one that was previously logged
[task 2021-12-02T11:25:00.818Z] 11:25:00     INFO - TEST-UNEXPECTED-FAIL | netwerk/test/browser/browser_103_telemetry.js | expected counts should match for EH_NUM_OF_HINTS_PER_PAGE at index 1 - 0 == 1 - JS frame :: resource://testing-common/TelemetryTestUtils.jsm :: assertHistogram :: line 296
[task 2021-12-02T11:25:00.819Z] 11:25:00     INFO - Stack trace:
[task 2021-12-02T11:25:00.820Z] 11:25:00     INFO - resource://testing-common/TelemetryTestUtils.jsm:assertHistogram:296
[task 2021-12-02T11:25:00.820Z] 11:25:00     INFO - chrome://mochitests/content/browser/netwerk/test/browser/browser_103_telemetry.js:null:33
[task 2021-12-02T11:25:00.821Z] 11:25:00     INFO - TEST-PASS | netwerk/test/browser/browser_103_telemetry.js | Should have found an entry for EH_NUM_OF_HINTS_PER_PAGE at index 1 - true == true - 
[task 2021-12-02T11:25:00.823Z] 11:25:00     INFO - Not taking screenshot here: see the one that was previously logged
[task 2021-12-02T11:25:00.825Z] 11:25:00     INFO - TEST-UNEXPECTED-FAIL | netwerk/test/browser/browser_103_telemetry.js | Should have found an entry for EH_FINAL_RESPONSE at index 0 - false == true - JS frame :: resource://testing-common/TelemetryTestUtils.jsm :: assertHistogram :: line 309
[task 2021-12-02T11:25:00.825Z] 11:25:00     INFO - Stack trace:
[task 2021-12-02T11:25:00.826Z] 11:25:00     INFO - resource://testing-common/TelemetryTestUtils.jsm:assertHistogram:309
[task 2021-12-02T11:25:00.828Z] 11:25:00     INFO - chrome://mochitests/content/browser/netwerk/test/browser/browser_103_telemetry.js:null:34
[task 2021-12-02T11:25:00.830Z] 11:25:00     INFO - Not taking screenshot here: see the one that was previously logged
[task 2021-12-02T11:25:00.831Z] 11:25:00     INFO - TEST-UNEXPECTED-FAIL | netwerk/test/browser/browser_103_telemetry.js | false == true - JS frame :: chrome://mochitests/content/browser/netwerk/test/browser/browser_103_telemetry.js :: <TOP_LEVEL> :: line 36
[task 2021-12-02T11:25:00.831Z] 11:25:00     INFO - Stack trace:
[task 2021-12-02T11:25:00.832Z] 11:25:00     INFO - chrome://mochitests/content/browser/netwerk/test/browser/browser_103_telemetry.js:null:36
[task 2021-12-02T11:25:00.832Z] 11:25:00     INFO - Leaving test bound 
[task 2021-12-02T11:25:00.835Z] 11:25:00     INFO - Entering test bound 
[task 2021-12-02T11:25:00.836Z] 11:25:00     INFO - Console message: [JavaScript Error: "The character encoding of the HTML document was not declared. The document will render with garbled text in some browser configurations if the document contains characters from outside the US-ASCII range. The character encoding of the page must be declared in the document or in the transfer protocol." {file: "http://example.com/browser/netwerk/test/browser/no_103_preload.html" line: 0}]
[task 2021-12-02T11:25:00.837Z] 11:25:00     INFO - GECKO(1570) | JavaScript error: http://example.com/browser/netwerk/test/browser/no_103_preload.html, line 13: TypeError: window.parent.ok is not a function

Resolved by performing backout.

Backout link : https://hg.mozilla.org/integration/autoland/rev/260e2362bbc3acecc2df9cc1561de8af348a20a2