GitLab

This reverts commit 62414cfc.

Reason for revert:

Findit (https://goo.gl/kROfz5) identified CL at revision 612971 as the
culprit for flakes in the build cycles as shown on:
https://findit-for-me.appspot.com/waterfall/flake/flake-culprit?key=ag9zfmZpbmRpdC1mb3ItbWVyQwsSDEZsYWtlQ3VscHJpdCIxY2hyb21pdW0vNjI0MTRjZmNkZThiNzA0NTk5ODQ3ZDZhY2M3MzFkMjU0NDc5NjU1Zgw

Sample Failed Build: https://ci.chromium.org/buildbot/chromium.mac/Mac10.11%20Tests/31315

Sample Failed Step: sync_integration_tests on (none) GPU on Mac on Mac-10.11

Sample Flaky Test: SingleClientSessionsSyncTest.NavigateThenCloseTabThenOpenTab

Original change's description:
> Avoid recycling sync tabs if commit pending
> 
> When a tab is closed, it's possible that the corresponding history
> hasn't been committed yet, and hence there is a risk that synced history
> is lost if the entity is recycled (for another tab that is opened).
> 
> In this patch, and behind a feature toggle, this issue is prevented by
> *not* freeing tab nodes while the sync entity is unsynced. Old tabs are
> excluded from this (to avoid problems with expired history) and a max
> cap is also introduced to the number of tabs in this state, in order to
> avoid memory regressions.
> 
> Bug: 882489
> Change-Id: I6dd796642f9553f2713a0814731897a4ffb13f0b
> Reviewed-on: https://chromium-review.googlesource.com/c/1356541
> Commit-Queue: Mikel Astiz <mastiz@chromium.org>
> Reviewed-by: Marc Treib <treib@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#612971}

Change-Id: I7735b817751abcbd18bded6a731115333ee50b26
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 882489, 910947
Reviewed-on: https://chromium-review.googlesource.com/c/1357999
Cr-Commit-Position: refs/heads/master@{#612976}