[SendTabToSelfHistory] Add an Opened State to STTS entries and protos

Also this change modifies the STTS bridge and observers to update that
state correctly.

Bug: 961913
Change-Id: I8a0b56c3ac01423790790957b68ae42bb68feab8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1607040
Commit-Queue: Jeffrey Cohen <jeffreycohen@chromium.org>
Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Reviewed-by: sebsg <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#661420}
14 files changed