Move performance dashboard upload logic to devtoolslib.

Move performance dashboard upload logic to devtoolslib.

This patch moves the logic that uploads chart_data to performance
dashboard, as well as the command line args spec that configures such
upload to devtoolslib, so that it can be shared between `mojo_benchmark`
and `perf_test_runner` (in a follow-up).

R=etiennej@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/aa9b52c175231c8677ac279a0630fda1b121ce50

[ppi, 2015-10-23 11:53:31]

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

[ppi, 2015-10-23 11:53:31]

Hi Etienne,

ptal.

[ppi, 2015-10-23 13:14:48]

Moved argparse config too in patch set 2, ptal.

[etiennej, 2015-10-23 15:05:15]

lgtm

[ppi, 2015-10-23 15:11:57]

Committed patchset #2 (id:20001) manually as
aa9b52c175231c8677ac279a0630fda1b121ce50 (presubmit successful).