Historically this directory has been a home for Valgrind and ThreadSanitizer. Since then other memory tools used in Chromium started squatting here and the name became confusing. We're replacing tools/valgrind with tools/memory/ new tools should go there. Attention: ThreadSanitizer v1 has been retired and files in this dir should not be used anymore. Please refer to http://dev.chromium.org/developers/testing/threadsanitizer-tsan-v2 for the instructions on using ThreadSanitizer v2. Namely, the suppressions now reside in base/debug/tsan_suppressions.cc