GitLab

Remove Extension::ScopedAllowLegacyExtensions and
ExtensionBrowserTest::ShouldAllowLegacyExtensionManifests(). These are
both unused now that all the affected tests have been updated.

Leave in the commandline flag kAllowLegacyExtensionManifests. This can
still be useful as a last resort for loading a v1 extension, and
there's no harm in leaving it in since we've removed all manifest
v1-specific handling (that is, all extensions loaded will effectively
be treated as v2).

Bug: 816679
Change-Id: I673bee01d00eaf7b82e1996da84f9b44e090aaf9
Reviewed-on: https://chromium-review.googlesource.com/1029000Reviewed-by: Istiaque Ahmed <lazyboy@chromium.org>
Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553860}