Handle control layouts with no repeat button

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=155625893

library/ui/src/main/java/com/google/android/exoplayer2/ui/PlaybackControlView.java

@@ -664,7 +664,7 @@ public class PlaybackControlView extends FrameLayout {
   }
   }
 
 
   private void updateRepeatModeButton() {
   private void updateRepeatModeButton() {
-    if (!isVisible() || !isAttachedToWindow) {
+    if (!isVisible() || !isAttachedToWindow || repeatToggleButton == null) {
       return;
       return;
     }
     }
     if (repeatToggleModes == REPEAT_TOGGLE_MODE_NONE) {
     if (repeatToggleModes == REPEAT_TOGGLE_MODE_NONE) {