GitLab

The change is related to CL:2291484. Add histogram information in
histograms.xml to make the histogram visible on chromedashboard.

BUG=b:160939695

Change-Id: Ic528934c18e0c3094e37cc16069c61bd5c931002
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2311983
Commit-Queue: Yu-Hsuan Hsu <yuhsuan@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#792376}