Merge changes from topic 'net-sync-aosp-with-stage-aosp' into stage-aosp-master

* changes:
  Captive portals: login activity probes like NetworkMonitor
  Logging improvements in CaptivePortalLoginActivity
  Captive portal systel log improvements
  Fix flaky IpPrefixTest.
  Removing bogus file added by mistake
  frameworks-test: adding missing @SmallTest
  Netd events: record connect() success/errno
  Add missing dependency.
  Show notification for always-on app VPN
  Implement metered tracking for NetworkStats summary queries.
  NetworkMonitor: send one DNS probe per web probe
  NetworkMonitor metrics: add first validation information
  APF: also drop any ICMPv6 RSs
  ConnectivityServiceTest: fix testAvoidBadWifiSettings
  Fix ConnectivityServiceTest testRequestBenchmark
  Switch over to new "time.android.com" NTP pool.
  Define API for metering network stats buckets.
  Refactored NetworkStatsServiceTest to use Mockito instead of EasyMock.
  Use @Ignore to explicitly disable a @test method.
  Fixed NetworkStatsServiceTest and converted it to JUnit4.
  VPN network stat accounting changes.
  ConnectivityThread: use lazy holder idiom
  ConnectivityManager: use ConnectivityThread looper
  ConnectivityManager: a simpler CallbackHandler
  Indicate the NsdServiceInfo attributes are only filled in for a resolved service.
  Add a null check for the OnStartTetheringCallback.
  TokenBucket for rate-limiting and throttling
  IpConnectivityMetrics reads buffer size in settings
  CaptivePortalLogin: set mixed content policy to compatibility.
  Add IP conn metrics to dumpsys and bug reports
  IpConnectivity metrics: add version number
  [CS] Remove timeout event after first available
  ApfTest: tag tests with @SmallTest or @MediumTest
  Unbreak TetherInterfaceStateMachineTest.
  Move the connectivity tests to frameworks/base/tests/net.
  De-guava BroadcastInterceptingContext and move it to testutils.
  Move FakeSettingsProvider to a common location.
  ConnectivityServiceTest: mark flaky test as such
  Add option to skip and avoid captive portals.
  ApfFilter: use elapsedRealTime for RA lifetime
  Do not synchronize boolean reads/writes
  ApfFilter: systematically use u8, u16, u32 getters
  Add fuzzing tests to ApfFilter RA processing
  Support timeouts for requestNetwork() invocations.
  Silence the obnoxious MTU 0 error message that occur when no MTU is specified for a given network.