e.g. failing run
https://logs.chromium.org/v/?s=chromium%2Fbb%2Fchromium.mac%2Fios-simulator%2F24295%2F%2B%2Frecipes%2Fsteps%2Fcomponents_unittests__iPhone_6s_Plus_iOS_11.0_%2F0%2Fstdout

Note: test suite is green because seconds try succeed when test is run alone.

OK ] ProfileSyncServiceTest.NoDisableSyncFlag (1 ms)
[ RUN      ] ProfileSyncServiceTest.MemoryPressureRecording
GMOCK WARNING:
Uninteresting mock function call - returning directly.
    Function call: RegisterDataTypes(0x7f97fb09d200, @0x7fff5b67a0d0 8-byte object <40-47 64-01 40-60 00-00>)
NOTE: You can safely ignore the above warning unless this call should not happen.  Do not suppress it by blindly adding an EXPECT_CALL() if you don't mean to enforce the call.  See https://github.com/google/googletest/blob/master/googlemock/docs/CookBook.md#knowing-when-to-expect for details.
Received signal 11 <unknown> 000000000000
 [0x0001085a01fd]
 [0x0001085a023d]
 [0x00010859e75c]
 [0x0001085a0024]
 [0x00011ef32b3a]
 [0x604000c20580]
 [0x00010877e1fb]
 [0x000108764b07]
 [0x000108766e74]
 [0x0001087492a0]
 [0x0001086164a1]
 [0x00010860dc00]
 [0x00010860dae1]
 [0x00010860d896]
 [0x000105274cd9]
 [0x000107c68f3e]
 [0x000107c45c72]
 [0x000107c45ba6]
 [0x000107c46c4d]
 [0x000107c47eec]
 [0x000107c54d99]
 [0x000107c6c01e]
 [0x000107c549b2]
 [0x000107c548ae]
 [0x00010acd3bd1]
 [0x00010acd304f]
 [0x00010acd7261]
 [0x000119dae609]
 [0x000116b4f374]
 [0x000116b4f032]
 [0x000116b4ebea]
 [0x000116b46604]
 [0x000116b45a89]
 [0x00011d37b9c6]
 [0x000117befd30]
 [0x00010acd7562]
 [0x00010acd2f2f]
 [0x000108489db2]
 [0x000108489ce4]
 [0x000108489c90]
 [0x000108489bac]
 [0x00010acdc59d]
 [0x00010acdc520]
 [0x00010767f439]
 [0x00011eb02d81]
 [0x000000000005]
[end of stack trace]
Calling _exit(1). Core file will not be generated.
2017-10-20 07:13:58.778 xcodebuild[8041:106386]  IDETestOperationsObserverDebug: Writing diagnostic log for test session to:
/var/folders/2j/22s2gz0s7hn48k32d47clxf80000gm/T/com.apple.dt.XCTest/IDETestRunSession-5721ABE5-BFDF-4608-B21E-15966889D26F/components_unittests-335A6457-4E14-43B9-B173-DB88D1D33E6B/Session-components_unittests-2017-10-20_071358-Zy3TJk.log
2017-10-20 07:13:58.778 xcodebuild[8041:106384] [MT] IDETestOperationsObserverDebug: (B9B78BC1-B072-4CDF-BA9D-12DBFFC07F18) Beginning test session components_unittests-B9B78BC1-B072-4CDF-BA9D-12DBFFC07F18 at 2017-10-20 07:13:58.778 with Xcode 9A235 on target <DVTiPhoneSimulator: 0x7f91ba6b1000> {
		SimDevice: iPhone 6s Plus (9F3E3601-5A98-4700-8D62-AFEF8734D38C, iOS 11.0, Booted)
} (11.0 (15A372))
/b/s/w/ir/src/out/Debug-iphonesimulator/iossim returned 65



The issue is caused by the levelDB database that register some globel observers which are never removed 

in third_party/leveldatabase/leveldb_chrome.cc:Globals()

Unittests should run with inmemory databases.