Disable tab syncing when history saving is disabled.
The history page shows the current tabs of synced devices. This works by
having the client upload its open tabs to the server, which feeds this
data into the history backend.
If history saving is disabled by policy then the opens tabs should not
be uploaded to the server. This also prevents them from showing up in
the history page.
BUG=292976,372108,393051
Review URL: https://codereview.chromium.org/
394223002
Cr-Commit-Position: refs/heads/master@{#292123}