chromeos: remove ShellDelegate::GetShellConnector()

Shell keeps a reference to the connector, so it shouldn't be needed on the
delegate.

BUG=none
TEST=none

Change-Id: I8e1342d4f887575f7b35d7a8a05233927743f222
Reviewed-on: https://chromium-review.googlesource.com/1155810
Commit-Queue: Scott Violet <sky@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579242}
18 files changed