TIF: add more documentation on Hardware session.
TIF: add more documentation on Hardware session.

Bug: 17909341
Change-Id: Ie537eb77b6ac4b63e4e9306c1781f84dd4be2719

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