Make TestableNetworkCallback understand blocked reasons. am: 5d4e7a5d36 am: b14d6f3014

Original change: https://android-review.googlesource.com/c/platform/frameworks/libs/net/+/1652229

Change-Id: I90fc1bd0b46d63e8dd0c4235ffa6241c7ec95aaa
tree: 39090e26fff2f86d2915dc7d941a0224ce6c539a
  1. staticlibs/