Protected Apps: Allow all system apps to see Protected Components

Change-Id: I5e12dd7cd05117a4e44a4bf3ee9f56ea6122ce15
UsbSettings: Add UMS mode support

Android only supports MTP and PTP mode in UsbSettings screen, this change
is to add USB mass storage mode.

Change-Id: I2e06e7484d92f0f8d61dee77b3060df712eb8b27