[automerger] [DO NOT MERGE] Update Platform Security String to 2019-03-01 for nyc-dev Bug:122541777 am: 7a403979d6 am: e56e5efec9 am: 87877d530a am: 33ecfffc1f skipped: 440db90921

Change-Id: I01f14495a15278d3e4a9b753be3c323eb596f24e