when running on ubuntu 16.04 vs 12.04, we have some failures, in this case we have this failure on c3 (opt/debug/asan): https://treeherder.mozilla.org/#/jobs?repo=try&revision=5ac0bd83bb7cd8ba2ecad1571c4d2038d8a70ba4&filter-searchStr=mochitest-chrome-3&selectedJob=73652282&group_state=expanded here is data from the debug log [0]: [task 2017-02-01T19:42:06.118338Z] 19:42:06 INFO - TEST-START | layout/base/tests/chrome/test_chrome_content_integration.xul [task 2017-02-01T19:42:06.119096Z] 19:42:06 INFO - ++DOMWINDOW == 38 (0x7fad5f9ee000) [pid = 1373] [serial = 66] [outer = 0x7fad5ffb3400] [task 2017-02-01T19:42:06.119953Z] 19:42:06 INFO - [1373] WARNING: No inner window available!: file /home/worker/workspace/build/src/dom/base/nsGlobalWindow.cpp, line 10078 [task 2017-02-01T19:42:06.120855Z] 19:42:06 INFO - ++DOCSHELL 0x7fad650c2800 == 10 [pid = 1373] [id = {f4ec3d58-b9c1-495d-ad50-8272d2adf5d1}] [task 2017-02-01T19:42:06.121927Z] 19:42:06 INFO - ++DOMWINDOW == 39 (0x7fad650c3800) [pid = 1373] [serial = 67] [outer = (nil)] [task 2017-02-01T19:42:06.122843Z] 19:42:06 INFO - ++DOMWINDOW == 40 (0x7fad650cf000) [pid = 1373] [serial = 68] [outer = 0x7fad650c3800] [task 2017-02-01T19:42:06.123624Z] 19:42:06 INFO - ++DOCSHELL 0x7fad61719000 == 11 [pid = 1373] [id = {43e46b98-94c1-45af-a4f6-e41193430781}] [task 2017-02-01T19:42:06.124611Z] 19:42:06 INFO - ++DOMWINDOW == 41 (0x7fad6ad5c400) [pid = 1373] [serial = 69] [outer = (nil)] [task 2017-02-01T19:42:06.125494Z] 19:42:06 INFO - ++DOMWINDOW == 42 (0x7fad6af71800) [pid = 1373] [serial = 70] [outer = 0x7fad6ad5c400] [task 2017-02-01T19:42:06.126408Z] 19:42:06 INFO - MEMORY STAT | vsize 1139MB | residentFast 259MB | heapAllocated 93MB [task 2017-02-01T19:42:06.127211Z] 19:42:06 INFO - --DOCSHELL 0x7fad650c2800 == 10 [pid = 1373] [id = {f4ec3d58-b9c1-495d-ad50-8272d2adf5d1}] [task 2017-02-01T19:42:06.127968Z] 19:42:06 INFO - TEST-OK | layout/base/tests/chrome/test_chrome_content_integration.xul | took 453ms [task 2017-02-01T19:42:06.128866Z] 19:42:06 INFO - ++DOMWINDOW == 43 (0x7fad6b7a6000) [pid = 1373] [serial = 71] [outer = 0x7fad5ffb3400] [task 2017-02-01T19:42:06.129811Z] 19:42:06 INFO - TEST-START | layout/base/tests/chrome/test_chrome_over_plugin.xul [task 2017-02-01T19:42:06.130610Z] 19:42:06 INFO - ++DOMWINDOW == 44 (0x7fad61069000) [pid = 1373] [serial = 72] [outer = 0x7fad5ffb3400] [task 2017-02-01T19:42:06.131406Z] 19:42:06 INFO - ++DOCSHELL 0x7fad61630800 == 11 [pid = 1373] [id = {8ceac254-39b8-4f42-be10-b324304afc11}] [task 2017-02-01T19:42:06.132248Z] 19:42:06 INFO - ++DOMWINDOW == 45 (0x7fad616b4000) [pid = 1373] [serial = 73] [outer = (nil)] [task 2017-02-01T19:42:06.133068Z] 19:42:06 INFO - ++DOMWINDOW == 46 (0x7fad616ba800) [pid = 1373] [serial = 74] [outer = 0x7fad616b4000] [task 2017-02-01T19:42:06.133849Z] 19:42:06 INFO - ++DOCSHELL 0x7fad657c5000 == 12 [pid = 1373] [id = {eed48c29-6170-4955-9f6c-4b53fe238685}] [task 2017-02-01T19:42:06.134513Z] 19:42:06 INFO - ++DOMWINDOW == 47 (0x7fad67f90400) [pid = 1373] [serial = 75] [outer = (nil)] [task 2017-02-01T19:42:06.135332Z] 19:42:06 INFO - ++DOMWINDOW == 48 (0x7fad68510000) [pid = 1373] [serial = 76] [outer = 0x7fad67f90400] [task 2017-02-01T19:42:06.136299Z] 19:42:06 INFO - For application/x-test found plugin libnptest.so [task 2017-02-01T19:42:06.137265Z] 19:42:06 INFO - ### XPCOM_MEM_BLOAT_LOG defined -- logging bloat/leaks to /tmp/tmpeLL7ZI.mozrunner/runtests_leaks_plugin_pid1442.log [task 2017-02-01T19:42:06.138040Z] 19:42:06 INFO - LoadPlugin() /tmp/tmpeLL7ZI.mozrunner/plugins/libnptest.so returned 7fa176bebd00 [task 2017-02-01T19:42:06.138797Z] 19:42:06 INFO - [NPAPI 1442] WARNING: '!compMgr', file /home/worker/workspace/build/src/xpcom/components/nsComponentManagerUtils.cpp, line 63 [task 2017-02-01T19:42:06.139683Z] 19:42:06 INFO - [NPAPI 1442] WARNING: NS_ENSURE_TRUE(InitStaticMembers()) failed: file /home/worker/workspace/build/src/modules/libpref/Preferences.cpp, line 1391 [task 2017-02-01T19:42:06.140434Z] 19:42:06 INFO - nsPluginNativeWindowGtk: NPPVpluginNeedsXEmbed=1 [task 2017-02-01T19:42:06.141266Z] 19:42:06 INFO - nsPluginNativeWindowGtk: call SetWindow with xid=0x2000097 [task 2017-02-01T19:42:06.142223Z] 19:42:06 INFO - nsPluginNativeWindowGtk: call SetWindow with xid=0x2000097 [task 2017-02-01T19:42:06.143087Z] 19:42:06 INFO - TEST-INFO | started process screentopng [task 2017-02-01T19:42:06.856764Z] 19:42:06 INFO - TEST-INFO | screentopng: exit 0 [task 2017-02-01T19:42:06.857734Z] 19:42:06 INFO - Buffered messages logged at 19:41:35 [task 2017-02-01T19:42:06.859143Z] 19:42:06 INFO - TEST-PASS | layout/base/tests/chrome/test_chrome_over_plugin.xul | plugin clip rect count [task 2017-02-01T19:42:06.860555Z] 19:42:06 INFO - TEST-PASS | layout/base/tests/chrome/test_chrome_over_plugin.xul | plugin clip rect left [task 2017-02-01T19:42:06.862069Z] 19:42:06 INFO - Buffered messages finished [task 2017-02-01T19:42:06.863560Z] 19:42:06 INFO - TEST-UNEXPECTED-FAIL | layout/base/tests/chrome/test_chrome_over_plugin.xul | plugin clip rect top - got +0, expected 50 [task 2017-02-01T19:42:06.864975Z] 19:42:06 INFO - SimpleTest.is@chrome://mochikit/content/tests/SimpleTest/SimpleTest.js:271:5 [task 2017-02-01T19:42:06.866276Z] 19:42:06 INFO - waitForPaint@chrome://mochitests/content/chrome/layout/base/tests/chrome/chrome_over_plugin_window.xul:41:9 [task 2017-02-01T19:42:06.867399Z] 19:42:06 INFO - setTimeout handler*waitForPaint@chrome://mochitests/content/chrome/layout/base/tests/chrome/chrome_over_plugin_window.xul:31:9 [task 2017-02-01T19:42:06.868420Z] 19:42:06 INFO - setTimeout handler*waitForPaint@chrome://mochitests/content/chrome/layout/base/tests/chrome/chrome_over_plugin_window.xul:31:9 [task 2017-02-01T19:42:06.869783Z] 19:42:06 INFO - setTimeout handler*waitForPaint@chrome://mochitests/content/chrome/layout/base/tests/chrome/chrome_over_plugin_window.xul:31:9 [task 2017-02-01T19:42:06.870841Z] 19:42:06 INFO - setTimeout handler*waitForPaint@chrome://mochitests/content/chrome/layout/base/tests/chrome/chrome_over_plugin_window.xul:31:9 [task 2017-02-01T19:42:06.872084Z] 19:42:06 INFO - setTimeout handler*waitForPaint@chrome://mochitests/content/chrome/layout/base/tests/chrome/chrome_over_plugin_window.xul:31:9 [task 2017-02-01T19:42:06.873257Z] 19:42:06 INFO - runTests@chrome://mochitests/content/chrome/layout/base/tests/chrome/chrome_over_plugin_window.xul:57:7 [task 2017-02-01T19:42:06.874419Z] 19:42:06 INFO - onload@chrome://mochitests/content/chrome/layout/base/tests/chrome/chrome_over_plugin_window.xul:1:1 [task 2017-02-01T19:42:06.875902Z] 19:42:06 INFO - TEST-PASS | layout/base/tests/chrome/test_chrome_over_plugin.xul | plugin clip rect right [task 2017-02-01T19:42:06.877356Z] 19:42:06 INFO - Not taking screenshot here: see the one that was previously logged [task 2017-02-01T19:42:06.878805Z] 19:42:06 INFO - TEST-UNEXPECTED-FAIL | layout/base/tests/chrome/test_chrome_over_plugin.xul | plugin clip rect bottom - got 100, expected 90 [task 2017-02-01T19:42:06.879977Z] 19:42:06 INFO - SimpleTest.is@chrome://mochikit/content/tests/SimpleTest/SimpleTest.js:271:5 [task 2017-02-01T19:42:06.880988Z] 19:42:06 INFO - waitForPaint@chrome://mochitests/content/chrome/layout/base/tests/chrome/chrome_over_plugin_window.xul:45:9 [task 2017-02-01T19:42:06.882117Z] 19:42:06 INFO - setTimeout handler*waitForPaint@chrome://mochitests/content/chrome/layout/base/tests/chrome/chrome_over_plugin_window.xul:31:9 [task 2017-02-01T19:42:06.883174Z] 19:42:06 INFO - setTimeout handler*waitForPaint@chrome://mochitests/content/chrome/layout/base/tests/chrome/chrome_over_plugin_window.xul:31:9 [task 2017-02-01T19:42:06.884347Z] 19:42:06 INFO - setTimeout handler*waitForPaint@chrome://mochitests/content/chrome/layout/base/tests/chrome/chrome_over_plugin_window.xul:31:9 [task 2017-02-01T19:42:06.885418Z] 19:42:06 INFO - setTimeout handler*waitForPaint@chrome://mochitests/content/chrome/layout/base/tests/chrome/chrome_over_plugin_window.xul:31:9 [task 2017-02-01T19:42:06.886701Z] 19:42:06 INFO - setTimeout handler*waitForPaint@chrome://mochitests/content/chrome/layout/base/tests/chrome/chrome_over_plugin_window.xul:31:9 [task 2017-02-01T19:42:06.887791Z] 19:42:06 INFO - runTests@chrome://mochitests/content/chrome/layout/base/tests/chrome/chrome_over_plugin_window.xul:57:7 [task 2017-02-01T19:42:06.888960Z] 19:42:06 INFO - onload@chrome://mochitests/content/chrome/layout/base/tests/chrome/chrome_over_plugin_window.xul:1:1 [task 2017-02-01T19:42:06.890490Z] 19:42:06 INFO - MEMORY STAT | vsize 1147MB | residentFast 260MB | heapAllocated 94MB [task 2017-02-01T19:42:06.891842Z] 19:42:06 INFO - --DOCSHELL 0x7fad61630800 == 11 [pid = 1373] [id = {8ceac254-39b8-4f42-be10-b324304afc11}] [task 2017-02-01T19:42:06.893138Z] 19:42:06 INFO - TEST-OK | layout/base/tests/chrome/test_chrome_over_plugin.xul | took 1626ms [task 2017-02-01T19:42:06.894639Z] 19:42:06 INFO - ++DOMWINDOW == 49 (0x7fad6af73c00) [pid = 1373] [serial = 77] [outer = 0x7fad5ffb3400] and the screenshot: https://public-artifacts.taskcluster.net/PvHkAWTJQNyzMqQ8IJEQXQ/0/public/test_info//mozilla-test-fail-screenshot_A2sFrQ.png the opt screenshot is more interesting: https://public-artifacts.taskcluster.net/KEA8iagcTma4upgX_-NOdA/0/public/test_info//mozilla-test-fail-screenshot_TKFdty.png I do wonder if the lack of a task bar at the top of the screen is changing some of the coordinates. :tnikkel, would you have any ideas on why this would be failing? [0] https://public-artifacts.taskcluster.net/PvHkAWTJQNyzMqQ8IJEQXQ/0/public/logs/live_backing.log

I don't think the taskbar at the top should be the problem, the test is looking at coords relative to the plugin itself. Hmm, the opt screenshot is weird. The plugin should be appearing inside another window, not the main window that is running the tests. And there should be things on top of it. So I'm guessing that window has already been closed and the plugin sticks around for either 1 frame or forever. Both seem wrong. I'm interested in what the screen looks like before the window is closed. If you comment out the window.close(); tester.finish(); in chrome_over_plugin_window.xul then the test should fail to end and timeout, I think that should generate a screenshot too.

This's fixed with try run https://treeherder.mozilla.org/#/jobs?repo=try&revision=476d56ec0da7ec34600657453d1bdc9fdb234289&filter-searchStr=c3&selectedJob=91365978