Merge changes from topic 'framework-net-aosp'

* changes:
  DO NOT MERGE: frameworks-test: adding missing @SmallTest
  DO NOT MERGE: Netd events: record connect() success/errno
  DO NOT MERGE: Add missing dependency.
  DO NOT MERGE: Show notification for always-on app VPN
  DO NOT MERGE: Implement metered tracking for NetworkStats summary queries.
  DO NOT MERGE: NetworkMonitor: send one DNS probe per web probe
  DO NOT MERGE: NetworkMonitor metrics: add first validation information
  DO NOT MERGE: APF: also drop any ICMPv6 RSs
  DO NOT MERGE: ConnectivityServiceTest: fix testAvoidBadWifiSettings
  DO NOT MERGE: Fix ConnectivityServiceTest testRequestBenchmark
  DO NOT MERGE: Switch over to new "time.android.com" NTP pool.
  DO NOT MERGE: Define API for metering network stats buckets.
  DO NOT MERGE: Refactored NetworkStatsServiceTest to use Mockito instead of EasyMock.
  DO NOT MERGE: Use @Ignore to explicitly disable a @test method.
  DO NOT MERGE: Fixed NetworkStatsServiceTest and converted it to JUnit4.
  DO NOT MERGE: VPN network stat accounting changes.
  DO NOT MERGE: ConnectivityThread: use lazy holder idiom
  DO NOT MERGE: ConnectivityManager: use ConnectivityThread looper
  DO NOT MERGE: ConnectivityManager: a simpler CallbackHandler
  DO NOT MERGE: Indicate the NsdServiceInfo attributes are only filled in for a resolved service.
  DO NOT MERGE: Add a null check for the OnStartTetheringCallback.