am ad44d814: am 3dc08220: am b57f236e: Merge changes Icf7d67e2,Ia914ec88,I2490ad75,Ie79f2d28 into mnc-dev

* commit 'ad44d81457971085a0b20fb42388010d76c79132':
  Add a hidden method to clear NetworkCapabilities.
  Fix javadoc error for requestNetwork.
  Simplify network callback handling code.
  Document and unhide CALLBACK_PRECHECK.
tree: 13b5941f4e1a840e537bd392fa5d45366da36b70
  1. core/
  2. services/
  3. tests/