Revert of [Extensions] Limit Extension WebUI (patchset #6 id:140001 of https://codereview.chromium.org/2452773002/ )

Reason for revert:
Suspect causing failure:
https://build.chromium.org/p/chromium.win/builders/Win7%20Tests%20%28dbg%29%281%29/builds/54207

Original issue's description:
> [Extensions] Limit ExtensionWebUI
>
> The bookmark manager needs a WebUI controller in order to change the
> transition type for links. However, right now, we're creating WebUI for
> every single extension.
>
> Instead, *only* create WebUI for the bookmark manager.
>
> Note that the ExtensionWebUI class is currently used for both this WebUI
> and for chrome url overrides, which are very separate concepts and
> should be split up, but I'll save that for a later CL.
>
> BUG=659798
>
> Committed: https://crrev.com/f9bc386d7f73366b45cb85848d27b4343facf45d
> Cr-Commit-Position: refs/heads/master@{#428747}

TBR=dbeam@chromium.org,sky@chromium.org,rdevlin.cronin@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=659798

Review-Url: https://codereview.chromium.org/2463153003
Cr-Commit-Position: refs/heads/master@{#428766}
4 files changed