Specify sender type  before changing state (browser/ui/cocoa)

Instead of using id as sender type this commit specifies which
types that are possible to recieve.

Bug: 803406
Change-Id: If5a6cfb0c0788b1e2a9e911ae05e9f7dc5e3840d
Reviewed-on: https://chromium-review.googlesource.com/1140166
Commit-Queue: Oscar Johansson <oscarj@opera.com>
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575637}
3 files changed