[CrOS Tether] Transform NetworkConnectionHandler to an interface.

chromeos/components/tether/tether_connector_unittest.cc

Index: chromeos/components/tether/tether_connector_unittest.cc
diff --git a/chromeos/components/tether/tether_connector_unittest.cc b/chromeos/components/tether/tether_connector_unittest.cc
index 3e54708ad375994b240142c754f15dd46564b07d..3187ddbcdc5204d9ee8d1d0529ca8a48c10710d1 100644
--- a/chromeos/components/tether/tether_connector_unittest.cc
+++ b/chromeos/components/tether/tether_connector_unittest.cc
@@ -60,6 +60,28 @@ class TestNetworkConnectionHandler : public NetworkConnectionHandler {
     InitiateTetherNetworkConnection(tether_network_guid, success_callback,
                                     error_callback);
   }
+
+  // NetworkConnectionHandler:
+  void ConnectToNetwork(const std::string& service_path,
+                        const base::Closure& success_callback,
+                        const network_handler::ErrorCallback& error_callback,
+                        bool check_error_state) override {}
+
+  void DisconnectNetwork(
+      const std::string& service_path,
+      const base::Closure& success_callback,
+      const network_handler::ErrorCallback& error_callback) override {}
+
+  bool HasConnectingNetwork(const std::string& service_path) override {
+    return false;
+  }
+
+  bool HasPendingConnectRequest() override { return false; }
+
+  void Init(NetworkStateHandler* network_state_handler,
+            NetworkConfigurationHandler* network_configuration_handler,
+            ManagedNetworkConfigurationHandler*
+                managed_network_configuration_handler) override {}
 };
 
 class FakeConnectTetheringOperation : public ConnectTetheringOperation {