Push more upload arguments logic from perf_test_runner -> devtools.

Push more upload arguments logic from perf_test_runner -> devtools.

This patch moves the check for required arguments and inferring of
revision and point_id into devtoolslib/perf_dashboard, so that it can be
shared between `perf_test_runner` and `mojo_benchmark`.

R=etiennej@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/32d6447076bec1e828295eabd1fe49ca60aa6931

[ppi, 2015-10-26 14:16:49]

ppi@chromium.org changed reviewers:
+ etiennej@chromium.org

[ppi, 2015-10-26 14:16:50]

Hi Etienne,

ptal.

[etiennej, 2015-10-26 16:46:00]

lgtm

[ppi, 2015-10-27 10:45:10]

Committed patchset #1 (id:1) manually as
32d6447076bec1e828295eabd1fe49ca60aa6931 (presubmit successful).