Dashboard - Add some timing around /add_histograms
Dashboard - Add some timing around /add_histograms

Bug: chromium:862666
Change-Id: I3a10eeb728d8b1ae632ac8c3debd6d233dc74ba1
Reviewed-on: https://chromium-review.googlesource.com/1134018
Reviewed-by: Ethan Kuefner <b3258c73b307e35b2725bc68d7434c38b3a2b146@chromium.org>
Commit-Queue: Simon Hatch <490a224d89645d3fea983d7189ce51bde0a00c1d@chromium.org>

catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult