Don't resume activity on start if there are activities pausing.

The path to start an activity if it isn't running was unconditionally
resuming the starting activity which we don't do if there are activities
pausing. It now starts the activity in a paused state if other activities
are pausing. It is then resumed when pause completes.

Also, improved logging in BoundsAnimationController and removed some
disabled code that has been in the codebase for 6yrs...

Bug: 26982752
Change-Id: Ie042fc938331127f1270fca1b5905b067b9dae7c