Expose API to detect when captive portal probe was blocked on Android

net/android/network_change_notifier_delegate_android.cc

Index: net/android/network_change_notifier_delegate_android.cc
diff --git a/net/android/network_change_notifier_delegate_android.cc b/net/android/network_change_notifier_delegate_android.cc
index 6bafb44dbe4f5b895c29e8578fa751267bb25427..346498e49b17df97ccbbe563318998d5585f2b31 100644
--- a/net/android/network_change_notifier_delegate_android.cc
+++ b/net/android/network_change_notifier_delegate_android.cc
@@ -142,6 +142,12 @@ NetworkChangeNotifierDelegateAndroid::GetCurrentDefaultNetwork() const {
   return default_network_;
 }
 
+bool NetworkChangeNotifierDelegateAndroid::GetCurrentNetworkCaptivePortal()
+    const {
+  return Java_NetworkChangeNotifier_getCurrentNetworkCaptivePortal(
+      base::android::AttachCurrentThread(), java_network_change_notifier_);
+}
+
 void NetworkChangeNotifierDelegateAndroid::GetCurrentlyConnectedNetworks(
     NetworkList* network_list) const {
   network_list->clear();