[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
am: bc19d8140c  -s ours

Change-Id: I7a7a9e0fa88aa5f1e70ad62bd5c1854eae885a1b