Add back accidentally deleted parameter in PlayerActivity.

A merge error in a previous change removed the drmSessionManager from
the player factory call.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=190769364

demos/main/src/main/java/com/google/android/exoplayer2/demo/PlayerActivity.java

@@ -340,7 +340,8 @@ public class PlayerActivity extends Activity
       lastSeenTrackGroupArray = null;
       eventLogger = new EventLogger(trackSelector);
 
-      player = ExoPlayerFactory.newSimpleInstance(renderersFactory, trackSelector);
+      player =
+          ExoPlayerFactory.newSimpleInstance(renderersFactory, trackSelector, drmSessionManager);
       player.addListener(new PlayerEventListener());
       player.addListener(eventLogger);
       player.addMetadataOutput(eventLogger);