[Extensions Callback Cleanup] EventRouter-related code

Remove usages of base::Callback and base::Bind (in favor of
base::[Once|Repeating]Callback and base::Bind[Once|Repeating]) and
update to passing by value when an instance is retained in
EventRouter-related code (including EventRouter,
LazyEventDispatcher, and callers).

Bug: 714018

Change-Id: I027c2eaccc521e89ef182aeac8c4d0d2523bcebb
Reviewed-on: https://chromium-review.googlesource.com/c/1391729
Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
Reviewed-by: Karan Bhatia <karandeepb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#619095}
15 files changed