Revert "Reland "wm: Update nested activation handling""

This reverts commit 77fbe34018de545f5b733709a2afcb1391ef1364.

Reason for revert: A test still fails with this.
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Linux%20TSan%20Tests/31030

Original change's description:
> Reland "wm: Update nested activation handling"
> 
> This is a reland of ecde845099001740fee119a82d45664e622d0ade
> 
> Original change's description:
> > wm: Update nested activation handling
> >
> > - NOTREACHED() and no-ope if the nested activation wants to change
> >   to a different active window other than the one being activated;
> > - Allow focus shift in nested activations as long as they don't
> >   change the window to be activated
> >
> > Bug: 908524
> > Test: FocusControllerApiTest.ActivateWhileActivating
> > Change-Id: I105c85bf2671c7e396fdcbedff7b8082f007f642
> > Reviewed-on: https://chromium-review.googlesource.com/c/1357017
> > Reviewed-by: Scott Violet <sky@chromium.org>
> > Reviewed-by: Mitsuru Oshima (gardener - slow) <oshima@chromium.org>
> > Commit-Queue: Xiyuan Xia <xiyuan@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#616346}
> 
> Bug: 908524, 914915
> Change-Id: Id0072941bfb0def54f093bcb771b2d8485c9b04e
> Reviewed-on: https://chromium-review.googlesource.com/c/1376726
> Reviewed-by: Scott Violet <sky@chromium.org>
> Commit-Queue: Xiyuan Xia <xiyuan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#616496}

TBR=xiyuan@chromium.org,sky@chromium.org,oshima@chromium.org

Change-Id: I8fd98eca46991af0cd6a780f44f7912c5d6bad13
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 908524, 914915
Reviewed-on: https://chromium-review.googlesource.com/c/1377477
Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Commit-Queue: Hitoshi Yoshida <peria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#616552}
3 files changed