Add android.net.CaptivePortal class for captive-portal-handling-app callbacks

This new class replaces the awkward string token and ConnectivityManager APIs
used by apps handling captive portals.

Bug:21343774
Change-Id: I1a2c69edb17322715bf8422bb4216b0ea60bfd59
diff --git a/Android.mk b/Android.mk
index e96a932..1de3625 100644
--- a/Android.mk
+++ b/Android.mk
@@ -181,6 +181,7 @@
 	core/java/android/hardware/location/IGeofenceHardwareMonitorCallback.aidl \
 	core/java/android/hardware/soundtrigger/IRecognitionStatusCallback.aidl \
 	core/java/android/hardware/usb/IUsbManager.aidl \
+	core/java/android/net/ICaptivePortal.aidl \
 	core/java/android/net/IConnectivityManager.aidl \
 	core/java/android/net/IEthernetManager.aidl \
 	core/java/android/net/IEthernetServiceListener.aidl \