Add SystemApi for captive portal metrics

The metrics go through NetworkMonitor in the NetworkStack so that they
can be upgraded to new metrics in the future.

Test: flashed, captive portal login works, metrics shown in events log
Bug: 112869080
Merged-In: I4bccfbd87bae5b2d65e45c7a5918aa45ab5d76e8
Change-Id: Ib5e2126788f8d56a00a56d7efcd33c5f9a37a6de

core/java/android/net/CaptivePortal.java

@@ -117,4 +117,17 @@ public class CaptivePortal implements Parcelable {
         } catch (RemoteException e) {
         }
     }
+
+    /**
+     * Log a captive portal login event.
+     * @hide
+     */
+    @SystemApi
+    @TestApi
+    public void logEvent(int eventId, String packageName) {
+        try {
+            ICaptivePortal.Stub.asInterface(mBinder).logEvent(eventId, packageName);
+        } catch (RemoteException e) {
+        }
+    }
 }

services/core/java/com/android/server/ConnectivityService.java

@@ -144,6 +144,7 @@ import com.android.internal.R;
 import com.android.internal.annotations.GuardedBy;
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.app.IBatteryStats;
+import com.android.internal.logging.MetricsLogger;
 import com.android.internal.net.LegacyVpnInfo;
 import com.android.internal.net.VpnConfig;
 import com.android.internal.net.VpnInfo;
@@ -2683,6 +2684,11 @@ public class ConnectivityService extends IConnectivityManager.Stub
                     EVENT_PROVISIONING_NOTIFICATION, PROVISIONING_NOTIFICATION_HIDE,
                     mNai.network.netId));
         }
+
+        @Override
+        public void logCaptivePortalLoginEvent(int eventId, String packageName) {
+            new MetricsLogger().action(eventId, packageName);
+        }
     }
 
     private boolean networkRequiresValidation(NetworkAgentInfo nai) {