https://chromium-review.googlesource.com/1082954 adds speedometer2 to crosperf/experiment_factory.py

Still to do:
- Once we have json from a few runs, update _estimated_stddev (in crosperf/benchmark.py).
- Update the json to columnio translation program (crostc_perf).
- Add to the performance dashboards.

Assigning to the new sheriff for remaining tasks.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/third_party/toolchain-utils/+/4358aa80c7e8fcd0709d7760a52855f2a8ecd24d

commit 4358aa80c7e8fcd0709d7760a52855f2a8ecd24d
Author: Yunlian Jiang <yunlian@google.com>
Date: Tue Jun 05 09:15:32 2018

add speedometer2 result format

This adds the speedometer2 result format to
default-telemetry-results.json.

BUG= chromium:849321 
TEST=run crosperf and it showed the result for speedometer2.

Change-Id: I8b824b6c1739a032bb15a706cee96d1f45c444ab
Reviewed-on: https://chromium-review.googlesource.com/1086292
Commit-Ready: Yunlian Jiang <yunlian@chromium.org>
Tested-by: Yunlian Jiang <yunlian@chromium.org>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>

[modify] https://crrev.com/4358aa80c7e8fcd0709d7760a52855f2a8ecd24d/crosperf/default-telemetry-results.json

This bug has an owner, thus, it's been triaged. Changing status to "assigned".