Rename PausableObject to ContextLifecycleStateObserver

Get rid of PauseState enum and use the FrameLifecycleState

BUG=907125

Change-Id: I15511c9a735f3393d8fdc0192398c244933f5ed0
Reviewed-on: https://chromium-review.googlesource.com/c/1458801
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Ken Buchanan <kenrb@chromium.org>
Reviewed-by: oysteine <oysteine@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Cr-Commit-Position: refs/heads/master@{#630896}
59 files changed