Fix playback tests

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=135100455

playbacktests/src/main/java/com/google/android/exoplayer2/playbacktests/gts/DashTest.java

@@ -19,6 +19,8 @@ import android.annotation.TargetApi;
 import android.media.MediaDrm;
 import android.media.UnsupportedSchemeException;
 import android.net.Uri;
+import android.os.Handler;
+import android.os.Looper;
 import android.test.ActivityInstrumentationTestCase2;
 import android.util.Log;
 import com.google.android.exoplayer2.C;
@@ -801,7 +803,7 @@ public final class DashTest extends ActivityInstrumentationTestCase2<HostActivit
 
     private DashTestTrackSelector(String audioFormatId, String[] videoFormatIds,
         boolean canIncludeAdditionalVideoFormats) {
-      super(null);
+      super(new Handler(Looper.getMainLooper()));
       this.audioFormatId = audioFormatId;
       this.videoFormatIds = videoFormatIds;
       this.canIncludeAdditionalVideoFormats = canIncludeAdditionalVideoFormats;