Merge "CDD: Allow display density to change, but require a fixed value for DENSITY_DEVICE_STABLE." into nougat-dev am: cdd069781b am: 93c0c1d0b9 am: d30eb71969
am: 182c86515a

Change-Id: Ic4d165a8c004219d70744303e1a7f725f5f165b3