Remove content from public_headers.

The file is unused, but we cannot safely delete it until we remove
the reference in a chromium gyp file.

BUG=skia:2350

Review URL: https://codereview.chromium.org/663913003
Revert of Start to vectorize SkTileGrid. (patchset #48 id:1670001 of https://codereview.chromium.org/634543004/)

Reason for revert:
breaks chrome GPU debug bots

Original issue's description:
> Start to vectorize SkTileGrid.
>
> This adds Sk4x.h to help.
>
> BUG=skia:3041
>
> Committed: https://skia.googlesource.com/skia/+/90c7992bfc6330f070f7704d63372a0ec8410170
>
> CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu12-ShuttleA-GTX660-x86-Debug-Trybot
>
> Committed: https://skia.googlesource.com/skia/+/958e9628d5f9a81aeafa78572cb4afc4b19a455a

TBR=reed@google.com,mtklein@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=skia:3041

Review URL: https://codereview.chromium.org/637863005
Move init() to Init() so that flag.Parse() can be called first.

Otherwise the --log_dir flag doesn't affect where glog output goes to.

TBR=humper
BUG=skia:

Review URL: https://codereview.chromium.org/667493002