Refactor and cleanup codes. No functional changes.

common/widevine_system_id.h

@@ -0,0 +1,22 @@
+////////////////////////////////////////////////////////////////////////////////
+// Copyright 2017 Google LLC.
+//
+// This software is licensed under the terms defined in the Widevine Master
+// License Agreement. For a copy of this agreement, please contact
+// widevine-licensing@google.com.
+////////////////////////////////////////////////////////////////////////////////
+//
+// Common Encryption (CENC) system ID for Widevine DRM.
+
+#ifndef COMMON_WIDEVINE_SYSTEM_ID_H_
+#define COMMON_WIDEVINE_SYSTEM_ID_H_
+
+#include <cstdint>
+
+namespace widevine {
+
+extern const uint8_t kWidevineSystemId[16];
+
+}  // namespace widevine
+
+#endif  // COMMON_WIDEVINE_SYSTEM_ID_H_