[DO NOT MERGE] Update Security String to 2017-04-01 on klp-dev am: 00c627eb...

[DO NOT MERGE] Update Security String to 2017-04-01 on klp-dev am: 00c627eb am: 5be6d3bb am: ed387848  -s ours am: 84702d99  -s ours am: d4661753 am: bc19d814  -s ours am: 53a64664 am: caff84dc am: 2f222829 am: 69586d29  -s ours am: 8f510b8c am: 34f2511b
am: 8bc2b6dc  -s ours

Change-Id: I6b2e462a21a905645465fa50e52ed53e2f9cbb80