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Having the views observe these notifications is strange -- they don't know when
page actions are updated in any other ways, so they shouldn't need to know for
this. Move the notifications to LocationBarController.

Bonuses:
- Less code! By 50 lines!
- Remove four deprecated notification uses!

This has a very loose dependency on https://codereview.chromium.org/508563003/.

BUG=407672

Review URL: https://codereview.chromium.org/505373002

Cr-Commit-Position: refs/heads/master@{#292225}