Fix header guards to comply with Google Coding Style.

The Google Style Guide says that every header file should have a
define guard and the format of the symbol name should be
  <PROJECT>_<PATH>_<FILE>_H_

This patch does all the minor fixes to comply with this and includes
a header guard for the bzip.h file, which didn't have it.

Also, the Copyright notice is adjusted to the Chromium OS code,
replacing "Chromium Authors" by "Chromium OS Authors".

BUG=None
TEST=build passes.

Change-Id: I6575cc307c464d60a5cb2b132cf1e46acb6500b5
Reviewed-on: https://chromium-review.googlesource.com/190445
Tested-by: Alex Deymo <deymo@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Commit-Queue: Alex Deymo <deymo@chromium.org>
diff --git a/simple_key_value_store.h b/simple_key_value_store.h
index 24a1d75..b8d2da4 100644
--- a/simple_key_value_store.h
+++ b/simple_key_value_store.h
@@ -6,8 +6,8 @@
 // key value store. Each key/value pair is stored on its own line and
 // separated by the first '=' on the line.
 
-#ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_SIMPLE_KEY_VALUE_STORE_H__
-#define CHROMEOS_PLATFORM_UPDATE_ENGINE_SIMPLE_KEY_VALUE_STORE_H__
+#ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_SIMPLE_KEY_VALUE_STORE_H_
+#define CHROMEOS_PLATFORM_UPDATE_ENGINE_SIMPLE_KEY_VALUE_STORE_H_
 
 #include <map>
 #include <string>
@@ -23,4 +23,4 @@
 }  // namespace simple_key_value_store
 }  // namespace chromeos_update_engine
 
-#endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_SIMPLE_KEY_VALUE_STORE_H__
+#endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_SIMPLE_KEY_VALUE_STORE_H_