Adding platform support check for NetworkObserver

net/android/network_change_notifier_android.cc

Index: net/android/network_change_notifier_android.cc
diff --git a/net/android/network_change_notifier_android.cc b/net/android/network_change_notifier_android.cc
index eac6589a8ef23ce88c33298923c733f61d570806..d957181c557bc1bc5ddb3c762350803834911603 100644
--- a/net/android/network_change_notifier_android.cc
+++ b/net/android/network_change_notifier_android.cc
@@ -162,6 +162,13 @@ void NetworkChangeNotifierAndroid::GetCurrentMaxBandwidthAndConnectionType(
                                                      connection_type);
 }
 
+bool NetworkChangeNotifierAndroid::AreNetworkHandlesCurrentlySupported() const {
+  // Notifications for API using NetworkHandles and querying using
+  // NetworkHandles only implemented for Android versions >= L.
+  return base::android::BuildInfo::GetInstance()->sdk_int() >=
+         base::android::SDK_VERSION_LOLLIPOP;
+}
+
 void NetworkChangeNotifierAndroid::GetCurrentConnectedNetworks(
     NetworkChangeNotifier::NetworkList* networks) const {
   delegate_->GetCurrentlyConnectedNetworks(networks);