Reland "Pull DocumentTabModel restoration logic into StorageDelegate" and run tests on pre-L devices
This reverts commit
5f207fa68d2caafcfc86eda9d6ca869bfde85203.
The code changed how we were adding missing tabs slightly, but it is still
functionally alright. Updated the tests to correct expectations.
Followed up by making the DocumentTabModel tests run on pre-L devices
because dealing with downstream breakages after-the-fact is untenable.
BUG=443772
Review URL: https://codereview.chromium.org/
1271813003
Cr-Commit-Position: refs/heads/master@{#341624}