Revert "Reland "macOS V2 Sandbox: Remove the feature flags.""

This reverts commit 4173f2019d1dada6fa06afa9b3bf7339f0ebcb01.

Reason for revert: The dependent CL was reverted so this has to be reverted.

https://chromium-review.googlesource.com/c/chromium/src/+/1278162

Original change's description:
> Reland "macOS V2 Sandbox: Remove the feature flags."
> 
> This is a reland of 5c4908e8ad7f53e2ddb2cd5631dc701558704b8c
> 
> Original change's description:
> > macOS V2 Sandbox: Remove the feature flags.
> >
> > The V2 sandbox is now default for all but the network and GPU processes
> > on macOS. This CL deletes the feature flag. A new experiment will be
> > introduced for the GPU process. The default case for the sandbox profile
> > switch is removed, because previous CHECK() failures were confusing to
> > diagnose. All profiles must now be handled explicitly, so Chrome won't
> > build if a new profile type isn't handled.
> >
> > Bug: 749839
> > CQ-Depend: 1268671
> > Change-Id: I0860d3a5148b0085be6a99dc01c4971602ee5582
> > Reviewed-on: https://chromium-review.googlesource.com/c/1269996
> > Reviewed-by: Robert Sesek <rsesek@chromium.org>
> > Reviewed-by: Mark Pearson <mpearson@chromium.org>
> > Reviewed-by: Avi Drissman <avi@chromium.org>
> > Commit-Queue: Greg Kerr <kerrnel@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#598128}
> 
> CQ-DEPEND=CL:1268671
> 
> Bug: 749839
> Change-Id: I91544907b640c572823f3aae3e29c0cfa003da51
> Reviewed-on: https://chromium-review.googlesource.com/c/1274888
> Reviewed-by: Avi Drissman <avi@chromium.org>
> Reviewed-by: Greg Kerr <kerrnel@chromium.org>
> Reviewed-by: Mark Pearson <mpearson@chromium.org>
> Commit-Queue: Greg Kerr <kerrnel@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#598822}

TBR=avi@chromium.org,mpearson@chromium.org,kerrnel@chromium.org,rsesek@chromium.org,mark@chromium.org

Change-Id: I301c95634bd447d35ef19948cf0488c0bf847e58
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 749839
Reviewed-on: https://chromium-review.googlesource.com/c/1278861
Reviewed-by: Greg Kerr <kerrnel@chromium.org>
Commit-Queue: Greg Kerr <kerrnel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599248}
7 files changed