Split network monitoring and portal probe events

This patches changes how captive portal tests and network lifecycle
events are logged as connectivity events:
  - it splits NetworkMonitorEvent into two event classes:
      - ValidationProbeEvent for logging individual probe events.
      - NetworkEvent for logging network connection, validation,
        lingering, and disconnection.
  - it removes the redundant CaptivePortalCheckResultEvent class.
    The information logged in CaptivePortalCheckResultEvent was already
    logged by NetworkMonitorEvent, but missing the evaluation durations.
    It is now logged by ValidationProbeEvent.
  - it removes the CaptivePortalStateChangeEvent class, which is now
    redundant with NetworkEvent, but missing evaluation durations.

In addition, it adds event logging when ConnectivityService puts a
network into lingering or removes a network from lingering.

Bug: 28204408
Change-Id: I8f9752e4d36175ecfcbd1545a01a41bad6e06ea4
diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index b965f64..b069361 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -72,6 +72,7 @@
 import android.net.UidRange;
 import android.net.Uri;
 import android.net.metrics.DefaultNetworkEvent;
+import android.net.metrics.NetworkEvent;
 import android.os.Binder;
 import android.os.Build;
 import android.os.Bundle;
@@ -2109,6 +2110,7 @@
 
     private void linger(NetworkAgentInfo nai) {
         nai.lingering = true;
+        NetworkEvent.logEvent(nai.network.netId, NetworkEvent.NETWORK_LINGER);
         nai.networkMonitor.sendMessage(NetworkMonitor.CMD_NETWORK_LINGER);
         notifyNetworkCallbacks(nai, ConnectivityManager.CALLBACK_LOSING);
     }
@@ -2122,6 +2124,7 @@
         nai.networkLingered.clear();
         if (!nai.lingering) return;
         nai.lingering = false;
+        NetworkEvent.logEvent(nai.network.netId, NetworkEvent.NETWORK_UNLINGER);
         if (VDBG) log("Canceling linger of " + nai.name());
         nai.networkMonitor.sendMessage(NetworkMonitor.CMD_NETWORK_CONNECTED);
     }