Add ScopedKeepAlive to c/b/lifetime

It moves from c/b/apps as it can be reused more generally across
//chrome/browser. It works with the new KeepAliveRegistry which is
the class keeping all the relevant information in an accessible place.

This patch also reuses ScopedKeepAlive instead of
c/b/ui/views/AutoKeepAlive

BUG=587926

Review URL: https://codereview.chromium.org/1708343002

Cr-Commit-Position: refs/heads/master@{#377913}
37 files changed