Examples:

https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/ios-simulator-full-configs/10672
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/ios-simulator-full-configs/10693
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/ios-simulator-full-configs/10707
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/ios-simulator-full-configs/10767
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/ios-simulator-full-configs/10831

For the last example, the bottom of the log output looks like this:

----
Test Suite 'All tests' passed at 2018-12-16 08:00:21.399.
	 Executed 21 tests, with 0 failures (0 unexpected) in 236.030 (236.056) seconds


Test session results and logs:
	/Users/chrome-bot/Library/Developer/Xcode/DerivedData/temporary-bdttjxltggrbqwdoemuthopabmsc/Logs/Test/Test-Transient Testing-2018.12.16_07-56-07--0800.xcresult

2018-12-16 08:00:21.789 xcodebuild[12250:153496] [MT] IDETestOperationsObserverDebug: 254.498 elapsed -- Testing started completed.
2018-12-16 08:00:21.789 xcodebuild[12250:153496] [MT] IDETestOperationsObserverDebug: 0.000 sec, +0.000 sec -- start
2018-12-16 08:00:21.789 xcodebuild[12250:153496] [MT] IDETestOperationsObserverDebug: 254.498 sec, +254.498 sec -- end
** TEST EXECUTE SUCCEEDED **
+-------------------------------------------------------------------------+
| End of shard 0                                                          |
|  Pending: 0.7s  Duration: 1495.7s  Bot: vm1175-m4  Exit: -15  TIMED_OUT |
+-------------------------------------------------------------------------+
Total duration: 1495.7s
----

It's a bit confusing to me, as it says "'All tests' passed" and "** TEST EXECUTE SUCCEEDED **", yet the result is "TIMED_OUT".