GitLab

Removing GetSiteForExtensionId() and updated the sole caller since it
doesn't actually need to use a site URL to accomplish what it was
trying to do.

- Removed extensions::util::GetSiteForExtensionId() to discourage new
  usage of site URLs.
- Updated file system logic to compute the origin it needs directly
  from the extension URL instead of calling GetSiteForExtensionId() to
  indirectly generate the same URL.

Bug: 1085275
Change-Id: I501e6ab3596597e4cdd8ee28df2c91f1104bed1f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2339608
Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
Auto-Submit: Aaron Colwell <acolwell@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#795615}