user_activity_benchmarks: Added tool for processing pprof and CWP data.

BUG=None
TEST=process_hot_functions_unitttest passes

Change-Id: I9956b34e9d1ca902a23be86dd8e21208462f0117
Reviewed-on: https://chrome-internal-review.googlesource.com/278697


Reviewed-by: Luis Lozano <llozano@chromium.org>
Tested-by: Evelina Dumitrescu <evelinad@google.com>
Reviewed-on: https://chromium-review.googlesource.com/435454


Commit-Ready: Luis Lozano <llozano@chromium.org>
Tested-by: Luis Lozano <llozano@chromium.org>