Revert of Accept invalid chrome-extension:// and chrome:// CSP tokens (patchset ...

Revert of Accept invalid chrome-extension:// and chrome:// CSP tokens (patchset #3 id:80001 of https://codereview.chromium.org/722233004/)

Reason for revert:
Need some extra comments before relanding

Original issue's description:
> Accept invalid chrome-extension:// and chrome:// CSP tokens
>
> Do not refuse to load the extension when the CSP contains
> "chrome-extension://", because there are some extensions in the wild
> that contains this token in the CSP. It is safe to accept this token
> because the invalid CSP token is ignored by Blink (together with an
> error message in the console, so the developer can fix the problem if
> they bother to look at the console).
>
> BUG=432227
> TBR=kalman@chromium.org
>
> Committed: https://crrev.com/67244e678279741947c09ba2ab18fbfec1707a97
> Cr-Commit-Position: refs/heads/master@{#304799}

TBR=kalman@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=432227

Review URL: https://codereview.chromium.org/739133003

Cr-Commit-Position: refs/heads/master@{#304832}