Added unittests for reference ECC implementation.

[ Merge of http://go/wvgerrit/114284 ]

The unittests check that the ECC keys are being created as expected
and that they can perform their basic operations.

Bug: 135283522
Test: oemcrypto_unittests
Change-Id: I1bdb26421ba47e1ab135f5ce5a54da304627a7c3

libwvdrmengine/oemcrypto/ref/test/oemcrypto_ref_test_utils.cpp

@@ -0,0 +1,20 @@
+// Copyright 2021 Google LLC. All Rights Reserved. This file and proprietary
+// source code may only be used and distributed under the Widevine License
+// Agreement.
+//
+//  Reference implementation of OEMCrypto APIs
+//
+#include "oemcrypto_ref_test_utils.h"
+
+#include <string>
+
+#include "cdm_random.h"
+
+namespace wvoec_ref {
+
+std::vector<uint8_t> RandomData(size_t length) {
+  const std::string data = wvcdm::CdmRandom::RandomData(length);
+  return std::vector<uint8_t>(data.begin(), data.end());
+}
+
+}  // namespace wvoec_ref