[Extensions Callback Cleanup] extensions/renderer/bindings code

Do the following clean-ups in extensions/renderer/bindings:
- Convert base::Callback to base::RepeatingCallback/base::OnceCallback
- Convert base::Bind to base::BindRepeating/base::BindOnce
- Pass callbacks by value when an instance is retained

In practice, all call sites here required a RepeatingCallback.

Bug: 714018
Change-Id: Id7cbffa21d5cda4210075086d083df5a4116dc6b
Reviewed-on: https://chromium-review.googlesource.com/c/1391417
Reviewed-by: Istiaque Ahmed <lazyboy@chromium.org>
Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#619105}
25 files changed