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
