Reland "Remove temporary headers in //ios/web/public."

This is a reland of 32e94a7933fce1bf7c0c5b1945118855edfa0241

Original change's description:
> Remove temporary headers in //ios/web/public.
> 
> This CL removes the temporary headers in //ios/web/public. Real headers
> are already moved into //ios/web/public/thread, and these temporary
> headers are kept to not break downstream.
> 
> Bug: 942244
> Change-Id: Ib8fe8a69c60c17125cb580180b622e5586d7eb3f
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1660563
> Reviewed-by: Rohit Rao <rohitrao@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#669217}

Bug: 942244
Change-Id: Id1c6f789821aea0e9fbd781bfc7b1644fcb09ecd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1660852
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Commit-Queue: Yi Su <mrsuyi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#669646}
4 files changed