Add LoadComponent API in ImageLoader dbus adapter.

chromeos/dbus/fake_image_loader_client.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chromeos/dbus/fake_image_loader_client.h"
 
 namespace chromeos {
 
 // ImageLoaderClient override:
 void FakeImageLoaderClient::RegisterComponent(
     const std::string& name,
     const std::string& version,
     const std::string& component_folder_abs_path,
     const BoolDBusMethodCallback& callback) {
   callback.Run(DBUS_METHOD_CALL_FAILURE, false);
 }
+void FakeImageLoaderClient::LoadComponent(
+    const std::string& name,
+    const StringDBusMethodCallback& callback) {
+  callback.Run(DBUS_METHOD_CALL_FAILURE, "");
+}
 
 }  // namespace chromeos