update_engine: fixed remaining linter and some spelling errors

Fixed remaining errors from cpplint as well as some spelling errors
mostly in comments.

BUG=None
TEST=FEATURES=test emerge-link update_engine

Change-Id: I484988ab846ac5a3c68c016ddccfb247f225ec27
Reviewed-on: https://chromium-review.googlesource.com/208897
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
diff --git a/payload_generator/metadata.h b/payload_generator/metadata.h
index 452e303..cf3d043 100644
--- a/payload_generator/metadata.h
+++ b/payload_generator/metadata.h
@@ -2,8 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_PAYLOAD_GENERATOR_METADATA_H_
-#define CHROMEOS_PLATFORM_UPDATE_ENGINE_PAYLOAD_GENERATOR_METADATA_H_
+#ifndef UPDATE_ENGINE_PAYLOAD_GENERATOR_METADATA_H_
+#define UPDATE_ENGINE_PAYLOAD_GENERATOR_METADATA_H_
+
+#include <string>
+#include <vector>
 
 #include "update_engine/payload_generator/delta_diff_generator.h"
 #include "update_engine/payload_generator/graph_types.h"
@@ -34,4 +37,4 @@
 
 };  // namespace chromeos_update_engine
 
-#endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_PAYLOAD_GENERATOR_METADATA_H_
+#endif  // UPDATE_ENGINE_PAYLOAD_GENERATOR_METADATA_H_