Replace hardcoded parameters

common/content_id_util.h

@@ -0,0 +1,30 @@
+////////////////////////////////////////////////////////////////////////////////
+// Copyright 2019 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.
+////////////////////////////////////////////////////////////////////////////////
+
+#ifndef COMMON_CONTENT_ID_UTIL_H_
+#define COMMON_CONTENT_ID_UTIL_H_
+
+#include "common/status.h"
+#include "protos/public/external_license.pb.h"
+#include "protos/public/license_protocol.pb.h"
+
+namespace widevine {
+
+// Get content identifier as a std::string from a SignedMessage that includes a
+// serialized ExternalLicenseRequest.
+Status GetContentIdFromSignedExternalLicenseRequest(
+    const SignedMessage& signed_message, std::string* content_id);
+
+// Get content identifier as a std::string from an ExternalLicenseRequest.
+Status GetContentIdFromExternalLicenseRequest(
+    const ExternalLicenseRequest& external_license_request,
+    std::string* content_id);
+
+}  // namespace widevine
+
+#endif  // COMMON_CONTENT_ID_UTIL_H_