Merge "libsync: add __INTRODUCED_IN annotations." am: 9d9c91acdc Change-Id: Iddd11dbd4e5169d794e272e850722f6c4982de23 Cr-Mirrored-From: https://chromium.googlesource.com/aosp/platform/system/core Cr-Mirrored-Commit: 832a5b0736b9ad879def762076acae387d8a5d76