Ensure onMediaItemTransition is sent for repeats of the same item

Currently, repeating the same item (via seekNext/Previous) implicitly
results in a seek to the default position of the current item, which
looks exactly the same as a direct seek. As a result, we don't send
onMediaItemTransition as we would for every other seekNext/Previous
call.

This can be fixed by explicitly marking the repeat case in the internal
BasePlayer/ExoPlayerImpl methods, so that the callback can be triggered.

Issue: google/ExoPlayer#10667
PiperOrigin-RevId: 481951788

library/common/src/main/java/com/google/android/exoplayer2/BasePlayer.java

@@ -21,6 +21,7 @@ import static java.lang.Math.min;
 import androidx.annotation.Nullable;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.util.Util;
 import com.google.android.exoplayer2.util.Util;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableList;
+import com.google.errorprone.annotations.ForOverride;
 import java.util.List;
 import java.util.List;
 
 
 /** Abstract base {@link Player} which implements common implementation independent methods. */
 /** Abstract base {@link Player} which implements common implementation independent methods. */
@@ -185,7 +186,12 @@ public abstract class BasePlayer implements Player {
   @Override
   @Override
   public final void seekToPreviousMediaItem() {
   public final void seekToPreviousMediaItem() {
     int previousMediaItemIndex = getPreviousMediaItemIndex();
     int previousMediaItemIndex = getPreviousMediaItemIndex();
-    if (previousMediaItemIndex != C.INDEX_UNSET) {
+    if (previousMediaItemIndex == C.INDEX_UNSET) {
+      return;
+    }
+    if (previousMediaItemIndex == getCurrentMediaItemIndex()) {
+      repeatCurrentMediaItem();
+    } else {
       seekToDefaultPosition(previousMediaItemIndex);
       seekToDefaultPosition(previousMediaItemIndex);
     }
     }
   }
   }
@@ -252,7 +258,12 @@ public abstract class BasePlayer implements Player {
   @Override
   @Override
   public final void seekToNextMediaItem() {
   public final void seekToNextMediaItem() {
     int nextMediaItemIndex = getNextMediaItemIndex();
     int nextMediaItemIndex = getNextMediaItemIndex();
-    if (nextMediaItemIndex != C.INDEX_UNSET) {
+    if (nextMediaItemIndex == C.INDEX_UNSET) {
+      return;
+    }
+    if (nextMediaItemIndex == getCurrentMediaItemIndex()) {
+      repeatCurrentMediaItem();
+    } else {
       seekToDefaultPosition(nextMediaItemIndex);
       seekToDefaultPosition(nextMediaItemIndex);
     }
     }
   }
   }
@@ -424,6 +435,17 @@ public abstract class BasePlayer implements Player {
         : timeline.getWindow(getCurrentMediaItemIndex(), window).getDurationMs();
         : timeline.getWindow(getCurrentMediaItemIndex(), window).getDurationMs();
   }
   }
 
 
+  /**
+   * Repeat the current media item.
+   *
+   * <p>The default implementation seeks to the default position in the current item, which can be
+   * overridden for additional handling.
+   */
+  @ForOverride
+  protected void repeatCurrentMediaItem() {
+    seekToDefaultPosition();
+  }
+
   private @RepeatMode int getRepeatModeForNavigation() {
   private @RepeatMode int getRepeatModeForNavigation() {
     @RepeatMode int repeatMode = getRepeatMode();
     @RepeatMode int repeatMode = getRepeatMode();
     return repeatMode == REPEAT_MODE_ONE ? REPEAT_MODE_OFF : repeatMode;
     return repeatMode == REPEAT_MODE_ONE ? REPEAT_MODE_OFF : repeatMode;

library/core/src/test/java/com/google/android/exoplayer2/ExoPlayerTest.java

@@ -8812,6 +8812,39 @@ public final class ExoPlayerTest {
   }
   }
 
 
   @Test
   @Test
+  public void seekToNextPrevious_singleItemRepeat_notifiesMediaItemTransition() throws Exception {
+    List<MediaItem> reportedMediaItems = new ArrayList<>();
+    List<Integer> reportedTransitionReasons = new ArrayList<>();
+    MediaSource mediaSource = FakeMediaSource.createWithWindowId(/* windowId= */ new Object());
+    ExoPlayer player = new TestExoPlayerBuilder(context).build();
+    player.addListener(
+        new Listener() {
+          @Override
+          public void onMediaItemTransition(@Nullable MediaItem mediaItem, int reason) {
+            reportedMediaItems.add(mediaItem);
+            reportedTransitionReasons.add(reason);
+          }
+        });
+    player.setMediaSource(mediaSource);
+    player.prepare();
+    runUntilPlaybackState(player, Player.STATE_READY);
+
+    player.setRepeatMode(Player.REPEAT_MODE_ALL);
+    player.seekToNextMediaItem();
+    player.seekToPreviousMediaItem();
+    player.release();
+
+    MediaItem expectedMediaItem = mediaSource.getMediaItem();
+    assertThat(reportedMediaItems)
+        .containsExactly(expectedMediaItem, expectedMediaItem, expectedMediaItem);
+    assertThat(reportedTransitionReasons)
+        .containsExactly(
+            Player.MEDIA_ITEM_TRANSITION_REASON_PLAYLIST_CHANGED,
+            Player.MEDIA_ITEM_TRANSITION_REASON_SEEK,
+            Player.MEDIA_ITEM_TRANSITION_REASON_SEEK);
+  }
+
+  @Test
   public void repeat_notifiesMediaItemTransition() throws Exception {
   public void repeat_notifiesMediaItemTransition() throws Exception {
     List<MediaItem> reportedMediaItems = new ArrayList<>();
     List<MediaItem> reportedMediaItems = new ArrayList<>();
     List<Integer> reportedTransitionReasons = new ArrayList<>();
     List<Integer> reportedTransitionReasons = new ArrayList<>();