[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 am: 53a64664c9 am: caff84dcbe am: 2f222829e0 am: 69586d29d7  -s ours am: 8f510b8ca1 am: 34f2511b65 am: 8bc2b6dc86
am: e62cac071f

Change-Id: I0832e83c9c8b992ce781a2762e812be601363e5f