UserAgent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.103 YaBrowser/18.7.0.2695 Yowser/2.5 Safari/537.36

Steps to reproduce the problem:
Just run:
1. env_chromium_unittests.exe --gtest_filter=ChromiumLevelDB.DeleteInMemoryDB

What is the expected behavior?
Test passed

What went wrong?
$ ./out/Debug.gn/env_chromium_unittests.exe --gtest_filter=ChromiumLevelDB.DeleteInMemoryDB
Note: Google Test filter = ChromiumLevelDB.DeleteInMemoryDB
[==========] Running 1 test from 1 test case.
[----------] Global test environment set-up.
[----------] 1 test from ChromiumLevelDB
[ RUN      ] ChromiumLevelDB.DeleteInMemoryDB
../../third_party/leveldatabase/env_chromium_unittest.cc(647): error: Value of: mem_env->FileExists(temp_path.AsUTF8Unsafe())
  Actual: true
Expected: false
Stack trace:
Backtrace:
        StackTraceGetter::CurrentStackTrace [0x00DE4D5A+90] (/distclang/../../third_party/googletest/custom/gtest/internal/custom/stack_trace_getter.cc:24)
        testing::internal::UnitTestImpl::CurrentOsStackTraceExceptTop [0x00E01F8A+74] (/distclang/../../third_party/googletest/src/googletest/src/gtest.cc:814)
        testing::internal::AssertHelper::operator= [0x00E01ABB+75] (/distclang/../../third_party/googletest/src/googletest/src/gtest.cc:386)
        leveldb_env::ChromiumLevelDB_DeleteInMemoryDB_Test::TestBody [0x00DB031F+6335] (/distclang/../../third_party/leveldatabase/env_chromium_unittest.cc:647)

[  FAILED  ] ChromiumLevelDB.DeleteInMemoryDB (35 ms)
[----------] 1 test from ChromiumLevelDB (35 ms total)

[----------] Global test environment tear-down
[==========] 1 test from 1 test case ran. (36 ms total)
[  PASSED  ] 0 tests.
[  FAILED  ] 1 test, listed below:
[  FAILED  ] ChromiumLevelDB.DeleteInMemoryDB

 1 FAILED TEST

Did this work before? No 

Chrome version: 67.0.3396.103  Channel: n/a
OS Version: 10.0
Flash Version: Shockwave Flash 30.0 r0

This is actually related to the MemEnv implementation, which is not intended to work with paths containing a backslash (Windows-like paths)