Fix cpplint errors.

The only non-obvious change here is the switch from dynamic_cast to
static_cast in three cases of down-casting in UpdateAttempter.
dynamic_cast is banned by style, nor does it add any safety in this
particular case (subsequent code dereferences the result right away
without checking whether it's null).

BUG=None
TEST=None

Change-Id: I9d49b46362feaf9c6fa13b2715ebe9fe50308a9a
Reviewed-on: https://chromium-review.googlesource.com/207470
Tested-by: Gilad Arnold <garnold@chromium.org>
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
diff --git a/system_state.h b/system_state.h
index b008095..21aeabd 100644
--- a/system_state.h
+++ b/system_state.h
@@ -2,8 +2,8 @@
 // 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_SYSTEM_STATE_H_
-#define CHROMEOS_PLATFORM_UPDATE_ENGINE_SYSTEM_STATE_H_
+#ifndef UPDATE_ENGINE_SYSTEM_STATE_H_
+#define UPDATE_ENGINE_SYSTEM_STATE_H_
 
 class MetricsLibraryInterface;
 
@@ -95,4 +95,4 @@
 
 }  // namespace chromeos_update_engine
 
-#endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_SYSTEM_STATE_H_
+#endif  // UPDATE_ENGINE_SYSTEM_STATE_H_