Many tests in PersonalDataManagerTest.* are dependent on wall clock time, thus occasionally flake when the bots are overloaded:

[ RUN      ] PersonalDataManagerTest.MergeProfile_UsageStats
personal_data_manager_unittest.cc(4477): error: Expected: (base::TimeDelta::FromMilliseconds(500)) > (base::Time::Now() - profile.use_date()), actual: 0.5s vs 0.56734s
[  FAILED  ] PersonalDataManagerTest.MergeProfile_UsageStats (905 ms)

Ideally, PersonalDataManagerTest should take a base::Clock so time can be mocked out and the tests are fully deterministic in this regard. Practically, the 500 ms timeouts should be increased so there is a lower chance of a flake.

Also see: https://build.chromium.org/p/chromium.win/builders/Win7%20Tests%20(dbg)(1)/builds/50521