Group account management methods and add some comments.
Group account management methods and add some comments.

Change-Id: I994142b557d21fbf75fc500d5ed1da9eceef6599

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base