[Greeter lock timeout] When the "Device Lock" be triggered, the lock timeout disappeared after reboot

[Roxanne Fan]

Environment:

Unit: Mako (Nexus4)
Product: Vivid
System version: r88

Steps:
1. Set a passcode for device: System Settings -> Security & Privacy -> Lock Phone -> Lock Security
2. Press power button to lock device
3. Enter incorrect lock code 7 times to trigger the 'Device Locked' display
4. Reboot phone

Expected result:
1. Phone reboots and locked greeter is displayed. Lock timeout should still be displayed.
2. User wait for timeout to expire
3. Enter correct passcode

Actual result:
1. Lock timeout disappeared.
2. User can enter correct password and get into system without waiting for timeout expired