policy: fix menu key for devices with no physical menu key

Initialize key behaviour correctly for the case where the respective key
isn't present in hardware.

Change-Id: I424f879dcf5e09c0897d7ebf7646efe36661d108
Fix virtual key press detection.

Virtual key events can be injected from anywhere, not just
PhoneWindowManager.

Change-Id: Ia9529c6534a208bf713912fc63f81a016754c6a6