GitLab

Add UMA for any HTMLTemplateElement usage.
We might want to add other UMA for different usages,
as https://crbug.com/922719#c1 requested, later.

Bug: 922719
Change-Id: Ib5f3c1a1bc573fb290d52a73ecbca38a5b86b8fa
Reviewed-on: https://chromium-review.googlesource.com/c/1436728Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Hayato Ito <hayato@chromium.org>
Cr-Commit-Position: refs/heads/master@{#626452}