/usr/lib/linux-tools/3.19.0-21-generic/perf is in linux-tools-3.19.0-21-generic 3.19.0-21.21~14.04.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/linux-tools/3.19.0-21-generic/../../linux-lts-vivid-tools-3.19.0-21/perf