Update Unit tests and reference code

This patch adds a suite of tests for OEMCrypto that verifying buffer
overflow and off-by-one errors. The reference code has also been
updated to pass these tests.

The ODK library and the OEMCrypto API have not changed since the
release of version 16.4.

util/test/test_sleep.h

@@ -1,6 +1,6 @@
 // Copyright 2019 Google LLC. All Rights Reserved. This file and proprietary
-// source code may only be used and distributed under the Widevine Master
-// License Agreement.
+// source code may only be used and distributed under the Widevine License
+// Agreement.
 //
 // TestSleep - Controls sleep and clock adjustment during tests.
 //
@@ -44,8 +44,8 @@ class TestSleep {
   // Roll the system clock forward to undo all previous calls to
   // RollBackSystemTime. Returns true on success.
   static bool ResetRollback() {
-    return total_clock_rollback_ == 0 ||
-           RollbackSystemTime(-total_clock_rollback_);
+    return total_clock_rollback_seconds_ == 0 ||
+           RollbackSystemTime(-total_clock_rollback_seconds_);
   }
 
   // Returns true if the system time can be rolled back. This is true on some
@@ -67,7 +67,7 @@ class TestSleep {
   static CallBack* callback_;
   // The sum of all calls to RollBackSystemTime. Kept so we can undo all changes
   // at the end of a test.
-  static int total_clock_rollback_;
+  static int total_clock_rollback_seconds_;
 };
 
 }  // namespace wvcdm