Revert "Revert "Have AMS.setFocusedActivityLocked() move the focus stack to the front""

This reverts commit 3426b72cff7f8eeea4c802f4f0fcae4b995e177a
and fixes bugs 19505341 19507107

Bug: 19219490
Bug: 19507107
Bug: 19505341
Change-Id: I7d6fc9fa41ed03bb7834facbb4c453e2561f13c9
3 files changed