GitLab

Add user action metrics for:
- Clicking to open the reading list
- Adding to the reading list from the Bookmark icon entry point
- Adding to the reading list from the tab context menu

Bug: 1163938
Change-Id: I95d655ce60f5b76c80f4d3b6a8490310befa8fac
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2622315
Commit-Queue: Caroline Rising <corising@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Reviewed-by: Dana Fried <dfried@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842589}