[DO NOT MERGE] Update Security String to 2017-04-01 on klp-dev am: 00c627eb31 am: 5be6d3bbb4 am: ed38784898  -s ours am: 84702d9919  -s ours
am: d466175346

Change-Id: I0fc9d82d3181bbf98cc5c35bd7f0be9c593b785d