Added top ten most frequent system calls by pid

Keeps a history of the peak top ten system calls by pid.

BUG=chromium-os:21206
TEST=x86

Change-Id: I11169d3887b04a4eaa807298fdceaf0dd6d2008c
Reviewed-on: http://gerrit.chromium.org/gerrit/8733
Tested-by: Paul Taysom <taysom@google.com>
Reviewed-by: Luigi Semenzato <semenzato@chromium.org>
7 files changed