De-dupe ACTION_DOWN events

Issue: #3259

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=168378650

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

@@ -996,13 +996,12 @@ public class PlaybackControlView extends FrameLayout {
       return false;
     }
     if (event.getAction() == KeyEvent.ACTION_DOWN) {
-      switch (keyCode) {
-        case KeyEvent.KEYCODE_MEDIA_FAST_FORWARD:
+      if (keyCode == KeyEvent.KEYCODE_MEDIA_FAST_FORWARD) {
         fastForward();
-          break;
-        case KeyEvent.KEYCODE_MEDIA_REWIND:
+      } else if (keyCode == KeyEvent.KEYCODE_MEDIA_REWIND) {
         rewind();
-          break;
+      } else if (event.getRepeatCount() == 0) {
+        switch (keyCode) {
           case KeyEvent.KEYCODE_MEDIA_PLAY_PAUSE:
             controlDispatcher.dispatchSetPlayWhenReady(player, !player.getPlayWhenReady());
             break;
@@ -1022,6 +1021,7 @@ public class PlaybackControlView extends FrameLayout {
             break;
         }
       }
+    }
     return true;
   }