[Cros SR logging] Implement UKM logging of launcher non-app results.

This adds the chrome-side of user interactions with non-app results in
the CrOS launcher. See go/cros-launcher-search-ranking-logging for
more details.

Bug: 972817
Change-Id: I602cd982a6972df93bdb920cc1f1bc793f6ab9e7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1706592
Commit-Queue: Tony Yeoman <tby@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Reviewed-by: calamity <calamity@chromium.org>
Reviewed-by: Jia Meng <jiameng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#681092}