This script uses the old dashboard format. It will eventually need to be switched to use the new Histograms format. This issue is to track this task. Mentioned on  issue 900677 :

"We have a nice library so you don't have to think about the json structure:
https://github.com/catapult-project/catapult/blob/master/tracing/tracing/value/histogram_set.py
Here's a doc to get started:
https://docs.google.com/document/d/1vWs1KOLDfv9YC8M_xfmHViwDxDC6wEWKjkQK1-nJmNs/edit

In HistogramSet, you'd add a Histogram named "score" with units=unitlessNumber and a Diagnostic named "stories" containing strings such as "DrawCallPerf_gl_render_to_texture_null". When those Histograms are uploaded to the chromeperf dashboard, it would add the data to a timeseries whose test path looks like master/bot/angle_perftests/score/DrawCallPerf_gl_render_to_texture_null. If necessary, please file a Speed>Dashboard bug to migrate the existing data from the old test paths to the new test paths."