Fix bug when Keyguard gets hidden.

We make sure in Keyguard that we only hide ourselves in
startKeyguardExitAnimation ourselves when we requested a hide.

In addition, this change also fixes a bug in WindowAnimator that
it should only call startKeyguardExitAnimation when Keyguard actually
requested a hide.

Bug: 15676717
Change-Id: I2279cccb9916985b7e9a2f41137878be5782cb9c
2 files changed