Revise a few metrics and add unit tests.

This is a merge of Widevine cl 39040.

A few of the metrics were not implemented, or implemented incorrectly in
O MR1. This cleans them up

Bug: 64001676

Test: Re-ran unit tests and added some additional tests. GPlay Movies check.

Change-Id: I1e8bcc36fecd76e72d853306075bc46d82f45161

libwvdrmengine/cdm/core/test/test_printers.cpp

@@ -568,6 +568,12 @@ void PrintTo(const enum CdmResponseType& value, ::std::ostream* os) {
     case LICENSE_REQUEST_INVALID_SUBLICENSE:
       *os << "LICENSE_REQUEST_INVALID_SUBLICENSE";
       break;
+    case CERT_PROVISIONING_EMPTY_SERVICE_CERTIFICATE:
+      *os << "CERT_PROVISIONING_EMPTY_SERVICE_CERTIFICATE";
+      break;
+    case LOAD_SYSTEM_ID_ERROR:
+      *os << "LOAD_SYSTEM_ID_ERROR";
+      break;
     default:
       *os                                        << "Unknown CdmResponseType";
       break;