Revert of Use tiles when encoding with VP9. (patchset #1 id:1 of https://codereview...

Revert of Use tiles when encoding with VP9. (patchset #1 id:1 of https://codereview.chromium.org/977663004/)

Reason for revert:
Breaks linux valgrind,
needs libvpx side fixes and roll, http://build.chromium.org/p/chromium.memory.fyi/builders/Linux%20Tests%20%28valgrind%29%283%29/builds/44420

Original issue's description:
> Use tiles when encoding with VP9.
>
> VP9's tile encoding feature allows for multithreaded parallelism on both the
> encoder and decoder side.
>
> TEST=Run remoting_perftests under VTune and see that two logical CPUs are used
> BUG=134202
>
> Committed: https://crrev.com/e67fefbf4f5a5a83ca8d487f422b09664dc4c8fe
> Cr-Commit-Position: refs/heads/master@{#319167}

TBR=wez@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=134202

Review URL: https://codereview.chromium.org/978133002

Cr-Commit-Position: refs/heads/master@{#319185}