Do not assert when drmInfo is null, because some DRM plugins
do not use acquireDrmInfo()/processDrmInfo() API.
Fix for bug 4449610.

Change-Id: I5401ee7e8ac90d0c80bbb5b12c506036d29b088d
diff --git a/tests/tests/drm/src/android/drm/cts/DRMTest.java b/tests/tests/drm/src/android/drm/cts/DRMTest.java
index c43bf4b..1d2d320 100644
--- a/tests/tests/drm/src/android/drm/cts/DRMTest.java
+++ b/tests/tests/drm/src/android/drm/cts/DRMTest.java
@@ -178,7 +178,9 @@
     }
 
     private void executeProcessDrmInfo(DrmInfo drmInfo, Config config) throws Exception {
-        assertNotNull("Failed on plugin: " + config.getPluginName(), drmInfo);
+        if (drmInfo == null) {
+            return;
+        }
 
         mDrmManagerClient.setOnEventListener(new OnEventListenerImpl(config));
         drmInfo.put(DrmInfoRequest.ACCOUNT_ID, config.getAccountId());