UpdateManager: Adjustments for cpplint.

- Rename header file guards.

- Added missing #includes.

Note that the linter still barks about C++11-style curly-braced member
initialization; there are abundant uses of this and we should probably
upstream a change to accommodate that.

BUG=None
TEST=Builds.

Change-Id: Icccc88e6e56e56f644536147cd88ae92462a1495
Reviewed-on: https://chromium-review.googlesource.com/205894
Tested-by: Gilad Arnold <garnold@chromium.org>
Reviewed-by: Alex Deymo <deymo@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
diff --git a/update_manager/update_manager.h b/update_manager/update_manager.h
index 5d7a045..131dcf0 100644
--- a/update_manager/update_manager.h
+++ b/update_manager/update_manager.h
@@ -2,8 +2,10 @@
 // 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_UPDATE_MANAGER_UPDATE_MANAGER_H_
-#define CHROMEOS_PLATFORM_UPDATE_ENGINE_UPDATE_MANAGER_UPDATE_MANAGER_H_
+#ifndef UPDATE_ENGINE_UPDATE_MANAGER_UPDATE_MANAGER_H_
+#define UPDATE_ENGINE_UPDATE_MANAGER_UPDATE_MANAGER_H_
+
+#include <string>
 
 #include <base/callback.h>
 #include <base/memory/ref_counted.h>
@@ -131,4 +133,4 @@
 // Include the implementation of the template methods.
 #include "update_engine/update_manager/update_manager-inl.h"
 
-#endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_UPDATE_MANAGER_UPDATE_MANAGER_H_
+#endif  // UPDATE_ENGINE_UPDATE_MANAGER_UPDATE_MANAGER_H_