Q12020 Flaky failing autotest function clearDataFromCache in qwebengineprofile

Here is the log from the incident

Coin task #1:http://coin/coin/integration/qt/qtwebengine/tasks/1583482896

Host OS version: macOS_10_14, target OS version macOS_10_14, Clang compiler

Log #1: http://coin/coin/logview/qt/qtwebengine/f3c9a45734feaf3dda96aca6c7e89e13fef96f40/MacOSMacOS_10_13x86_64MacOSMacOS_10_13x86_64Clangqtci-macos-10.13-x86_64-2-dc4a1e/6192eacfcf35fd8497c1ec12c5ae1e236cf47632/test_1583482969

********* Start testing of tst_QWebEngineProfile *********
...
FAIL! : tst_QWebEngineProfile::clearDataFromCache() 'sizeBeforeClear > totalSize(cacheDir)' returned FALSE. ()
Loc: [tst_qwebengineprofile.cpp(256)]
...
Totals: 25 passed, 1 failed, 0 skipped, 0 blacklisted, 15621ms
********* Finished testing of tst_QWebEngineProfile *********
...
********* Start testing of tst_QWebEngineProfile *********
Config: Using QtTest library 5.15.0, Qt 5.15.0 (x86_64-little_endian-lp64 shared (dynamic) release build; by Clang 10.0.0 (clang-1000.11.45.5) (Apple))
...
FAIL! : tst_QWebEngineProfile::clearDataFromCache() 'sizeBeforeClear > totalSize(cacheDir)' returned FALSE. ()
Loc: [tst_qwebengineprofile.cpp(256)]
...
Totals: 2 passed, 1 failed, 0 skipped, 0 blacklisted, 1950ms
********* Finished testing of tst_QWebEngineProfile *********

Externally accessible log: https://testresults.qt.io/coin/integration/qt/qtwebengine/tasks/1583482896

The wanted action

• Please delegate this task to a suitable developer
• Fix the autotest flakiness in all affected versions, not just one. 
• Cherry-pick the fix to all relevant branches
• Mark the fix versions to Jira
• Try to fix the actual issue instead of just blacklisting the test function

Guidelines for debugging

Please see the internal page https://intranet.qt.io/display/QTRD/Metrics+Guidelines+for+Grafana+Tool+for+Autotests+with+Issues

How to locate the failed flaky test:

Please open the link to the Grafana dashboard showing the failure history of the test:

https://testresults.qt.io/grafana/d/5GKDJSPZz/02-qt-framework-please-fix-these-flaky-tests-random-fails?orgId=1&from=now%2Fy&to=now&var-project=qt%2Fqtwebengine&var-testcase=tests%2Fauto%2Fwidgets%2Fqwebengineprofile&var-testfunction=clearDataFromCache&var-branch=5.12&var-branch=5.13&var-branch=5.14&var-branch=5.15&var-branch=dev&var-inter=24h

Please see the panel List of the recent flaky tests (both passed and failed). Sort it based on the results to see the failed instances. 

Please open the links to the Coin tasks containing the logs. Please see the test section containing state "Error" and open corresponding logs. 

Need to know more about the test binary execution history?

Please see this Grafana dashboard: 

https://testresults.qt.io/grafana/d/C-1oxSEWz/04-qt-framework-please-see-the-flakiness-history-of-tests?orgId=1&from=now%2Fy&to=now&var-project=qt%2Fqtwebengine&var-testcase=tests%2Fauto%2Fwidgets%2Fqwebengineprofile&var-testfunction=All&var-branch=5.12&var-branch=5.13&var-branch=5.14&var-branch=5.15&var-branch=dev&var-inter=24h