/usr/lib/linux-tools/3.19.0-68-generic/perf is in linux-tools-3.19.0-68-generic 3.19.0-68.76~14.04.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/linux-tools/3.19.0-68-generic/../../linux-lts-vivid-tools-3.19.0-68/perf