Introduce IWindowManager.keyguardGoingAway to notify that Keyguard wants to dismiss it self. This method starts the state machine in WindowAnimator which animates in the activity behind the keyguard. Animating out the keyguard is done by the StatusBar/Keyguard software when it receives the startKeyguardExitAnimation() callback. Bug: 14118756 Change-Id: Id3b8f41189410bad808b4892fbec74245e59efce