Move functions in blink::WebCORS to platform/loader/cors/cors.{h,cc}

blink::WebCORS is not used by non-blink. blink/public is a wrong place
for blink::WebCORS.
Move the functions and change parameters from "web types" to
platform types.

Bug: 889726
Change-Id: Ic9fa44d67b035e8229034fdc9321b555b6a4f828
Reviewed-on: https://chromium-review.googlesource.com/c/1325582
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Zhuoyu Qian <zhuoyu.qian@samsung.com>
Cr-Commit-Position: refs/heads/master@{#607140}
13 files changed