Revert of Enable the OOP PDF viewer as the default (patchset #1 id:1 of https://codereview.chromium.org/748553003/)

Reason for revert:
This got merged badly and flipped the wrong flag.

Original issue's description:
> Enable the OOP PDF viewer as the default
>
> BUG=303491
>
> Committed: https://crrev.com/ff54748f98853a5fedb2010c0c0f6748ded9cf2e
> Cr-Commit-Position: refs/heads/master@{#311010}

TBR=thestig@chromium.org,sammc@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=303491

Review URL: https://codereview.chromium.org/835273005

Cr-Commit-Position: refs/heads/master@{#311214}
1 file changed