Revert of Enable the bootstrap sandbox by default. (patchset #3 id:40001 of https...

Revert of Enable the bootstrap sandbox by default. (patchset #3 id:40001 of https://codereview.chromium.org/1352623003/ )

Reason for revert:
Caused Mac 10.10 layout failures: http://build.chromium.org/p/chromium.webkit/builders/WebKit%20Mac10.10/builds/4593

Original issue's description:
> Enable the bootstrap sandbox by default.
>
> This will place renderer processes under the bootstrap sandbox. This can be
> disabled with --disable-bootstrap-sandbox.
>
> BUG=367863
>
> Committed: https://crrev.com/2dded5291bc5e9427721e1a06c74f2a80a86e8fa
> Cr-Commit-Position: refs/heads/master@{#350006}

TBR=avi@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=367863

Review URL: https://codereview.chromium.org/1355043004

Cr-Commit-Position: refs/heads/master@{#350065}