GitLab

Add a histogram to collect aggregate watchtime for
all media feeds so we can see the distribution of
watchtimes.

BUG=1110373

Change-Id: I472cff204e299efabe9f0b90949b14ca3d0fd912
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2432590Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Tommy Steimel <steimel@chromium.org>
Commit-Queue: Becca Hughes <beccahughes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#811817}