Consistently use SHA256 for filenames (previously, MD5 and SHA1 were used). am: 72a67b76c6 am: 4b636830cd am: 074067b725 am: d34002fb87 am: ffe6f59740 am: 32f61d3438 am: 49966bab17
am: 5ba121e612

Change-Id: I67dc5df68d0f7c964f32dee1325cc8e276681679