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) {
+        }
+    }
 }

core/java/android/net/ICaptivePortal.aidl

@@ -22,4 +22,5 @@ package android.net;
  */
 oneway interface ICaptivePortal {
     void appResponse(int response);
+    void logEvent(int eventId, String packageName);
 }

core/java/android/net/INetworkMonitorCallbacks.aidl

@@ -26,4 +26,5 @@ oneway interface INetworkMonitorCallbacks {
     void notifyPrivateDnsConfigResolved(in PrivateDnsConfigParcel config);
     void showProvisioningNotification(String action);
     void hideProvisioningNotification();
+    void logCaptivePortalLoginEvent(int eventId, String packageName);
 }