windows_host_engine_test has gotten very flaky since thread merging #167418
Description
See https://ci.chromium.org/ui/p/flutter/builders/prod/Windows%20Production%20Engine%20Drone:
Failures before (~0)
Failures after (~many)
Example failures:
- https://cr-buildbucket.appspot.com/build/8717225845221013761
- https://cr-buildbucket.appspot.com/build/8717226941240514737
- https://cr-buildbucket.appspot.com/build/8717227996159337729
- https://cr-buildbucket.appspot.com/build/8717232472223529057
- https://cr-buildbucket.appspot.com/build/8717258058718895505
- https://cr-buildbucket.appspot.com/build/8717281729071274833
- https://cr-buildbucket.appspot.com/build/8717284529279395361
- https://cr-buildbucket.appspot.com/build/8717296510704283681
Some excerpts from above:
EmbedderTest.PlatformThreadIsolatesWithCustomPlatformTaskRunner
WindowsTest.LaunchMainHasNoOutputI am marking this task as bringup: true and assigning to @knopp and @loic-sharma to investigate.