Central as Beta simulation

Treeherder link: https://treeherder.mozilla.org/#/jobs?repo=try&resultStatus=testfailed%2Cbusted%2Cexception&revision=5463c8f098273d9b96001b6089d2f666b9bc07a7&selectedTaskRun=bEhvKcbRSRGAQnSfgcpmqg.0

Failure log:
https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=314796511&repo=try&lineNumber=3872

[task 2020-09-03T13:28:18.419Z] 13:28:18 INFO - TEST-START | browser/components/urlbar/tests/unit/test_search_suggestions_aliases.js
[task 2020-09-03T13:28:21.161Z] 13:28:21 WARNING - TEST-UNEXPECTED-FAIL | browser/components/urlbar/tests/unit/test_search_suggestions_aliases.js | xpcshell return code: 0
[task 2020-09-03T13:28:21.161Z] 13:28:21 INFO - TEST-INFO took 2746ms
[task 2020-09-03T13:28:21.162Z] 13:28:21 INFO - >>>>>>>
[task 2020-09-03T13:28:21.162Z] 13:28:21 INFO - (xpcshell/head.js) | test MAIN run_test pending (1)
[task 2020-09-03T13:28:21.162Z] 13:28:21 INFO - (xpcshell/head.js) | test run_next_test 0 pending (2)
[task 2020-09-03T13:28:21.162Z] 13:28:21 INFO - (xpcshell/head.js) | test MAIN run_test finished (2)
[task 2020-09-03T13:28:21.162Z] 13:28:21 INFO - running event loop
[task 2020-09-03T13:28:21.163Z] 13:28:21 INFO - browser/components/urlbar/tests/unit/test_search_suggestions_aliases.js | Starting initXPCShellDependencies
[task 2020-09-03T13:28:21.163Z] 13:28:21 INFO - (xpcshell/head.js) | test initXPCShellDependencies pending (2)
[task 2020-09-03T13:28:21.163Z] 13:28:21 INFO - (xpcshell/head.js) | test run_next_test 0 finished (2)
[task 2020-09-03T13:28:21.163Z] 13:28:21 INFO - (xpcshell/head.js) | test run_next_test 1 pending (2)
[task 2020-09-03T13:28:21.163Z] 13:28:21 INFO - (xpcshell/head.js) | test initXPCShellDependencies finished (2)
[task 2020-09-03T13:28:21.164Z] 13:28:21 INFO - browser/components/urlbar/tests/unit/test_search_suggestions_aliases.js | Starting setup
[task 2020-09-03T13:28:21.164Z] 13:28:21 INFO - (xpcshell/head.js) | test setup pending (2)
[task 2020-09-03T13:28:21.164Z] 13:28:21 INFO - "Adding engine: engine-suggestions.xml"
[task 2020-09-03T13:28:21.164Z] 13:28:21 INFO - "Adding engine from URL: http://localhost:9000/data/engine-suggestions.xml"
[task 2020-09-03T13:28:21.164Z] 13:28:21 INFO - (xpcshell/head.js) | test run_next_test 1 finished (2)
[task 2020-09-03T13:28:21.164Z] 13:28:21 INFO - PID 26792 | console.error: SearchCache: "_readCacheFile: Error reading cache file:" (new Error("", "(unknown module)"))
[task 2020-09-03T13:28:21.164Z] 13:28:21 INFO - "Observed engine-added for engine-suggestions.xml"
[task 2020-09-03T13:28:21.164Z] 13:28:21 INFO - "Observed engine-loaded for engine-suggestions.xml"
[task 2020-09-03T13:28:21.164Z] 13:28:21 INFO - (xpcshell/head.js) | test run_next_test 2 pending (2)
[task 2020-09-03T13:28:21.164Z] 13:28:21 INFO - (xpcshell/head.js) | test setup finished (2)
[task 2020-09-03T13:28:21.164Z] 13:28:21 INFO - browser/components/urlbar/tests/unit/test_search_suggestions_aliases.js | Starting nonTokenAlias_noTrailingSpace
[task 2020-09-03T13:28:21.164Z] 13:28:21 INFO - (xpcshell/head.js) | test nonTokenAlias_noTrailingSpace pending (2)
[task 2020-09-03T13:28:21.166Z] 13:28:21 INFO - TEST-PASS | browser/components/urlbar/tests/unit/test_search_suggestions_aliases.js | nonTokenAlias_noTrailingSpace - [nonTokenAlias_noTrailingSpace : 41] "moz" == "moz"
[task 2020-09-03T13:28:21.166Z] 13:28:21 INFO - "Creating new queryContext with searchString: moz"
[task 2020-09-03T13:28:21.167Z] 13:28:21 INFO - (xpcshell/head.js) | test run_next_test 2 finished (2)
[task 2020-09-03T13:28:21.167Z] 13:28:21 INFO - "Actual results: [{"type":2,"source":3,"rowIndex":-1,"suggestedIndex":-1,"heuristic":true,"payload":{"engine":"TestDefaultEngine","query":"moz"},"payloadHighlights":{"engine":[],"icon":[],"query":[]},"providerName":"HeuristicFallback","providerType":1}]"
[task 2020-09-03T13:28:21.167Z] 13:28:21 WARNING - TEST-UNEXPECTED-FAIL | browser/components/urlbar/tests/unit/test_search_suggestions_aliases.js | nonTokenAlias_noTrailingSpace - [nonTokenAlias_noTrailingSpace : 1] Found the expected number of results. - 1 == 2

Beta simulation try with both this bug and bug 1663025: https://treeherder.mozilla.org/#/jobs?repo=try&revision=50c92ff2781e8b5fc6e4a2e46b50ff0945c52ae2

The "Search in a Private Window" result is included only in Nightly builds, so
this test needs to either enable the corresponding pref, or disable the pref and
remove that result from the expected results. This patch does the latter.

https://hg.mozilla.org/mozilla-central/rev/181dc0502862

Verified fixed in beta-sims: https://treeherder.mozilla.org/#/jobs?repo=try&revision=289b2063b0e3b188107cf49e0ce2c34c4dc38bcf&searchStr=linux%2C18.04%2Cx64%2Casan%2Copt%2Cxpcshell%2Ctests%2Ctest-linux1804-64-asan%2Fopt-xpcshell-e10s%2Cx3&selectedTaskRun=a2s_vNCNQhq8tGv0Gg8xfg.0