OOR-CORS: Remove BlinkCORS supporting code outside Blink

As OOR-CORS was fully launched, this patch removes BlinkCORS
supporting code that exists outside Blink.

We still have some dead code in Blink, and subsequent cleanup
changes will remove them all.

Bug: 1053866
Change-Id: Ibe9f913d3cc9f183d6e681516996f1bc6cc58b96
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2397458


Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Karan Bhatia <karandeepb@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: John Abd-El-Malek <jam@chromium.org>
Auto-Submit: Takashi Toyoshima <toyoshim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#805644}