Add missing equals to MergingMediaPeriod.ForwardingTrackSelection

This causes a bug where the forwarded selections are no longer
assumed equal and the child MediaPeriods will think they need
to reset streams even though the selection stayed the same.

Issue: Issue: #10248
PiperOrigin-RevId: 449454038

library/core/src/main/java/com/google/android/exoplayer2/source/MergingMediaPeriod.java

@@ -607,5 +607,25 @@ public boolean blacklist(int index, long exclusionDurationMs) {
     public boolean isBlacklisted(int index, long nowMs) {
       return trackSelection.isBlacklisted(index, nowMs);
     }
+
+    @Override
+    public boolean equals(@Nullable Object o) {
+      if (this == o) {
+        return true;
+      }
+      if (!(o instanceof ForwardingTrackSelection)) {
+        return false;
+      }
+      ForwardingTrackSelection that = (ForwardingTrackSelection) o;
+      return trackSelection.equals(that.trackSelection) && trackGroup.equals(that.trackGroup);
+    }
+
+    @Override
+    public int hashCode() {
+      int result = 17;
+      result = 31 * result + trackGroup.hashCode();
+      result = 31 * result + trackSelection.hashCode();
+      return result;
+    }
   }
 }

library/core/src/test/java/com/google/android/exoplayer2/source/MergingMediaPeriodTest.java

@@ -34,6 +34,7 @@
 import com.google.android.exoplayer2.trackselection.FixedTrackSelection;
 import com.google.android.exoplayer2.upstream.DefaultAllocator;
 import com.google.common.collect.ImmutableList;
+import java.util.Arrays;
 import java.util.concurrent.CountDownLatch;
 import org.checkerframework.checker.nullness.compatqual.NullableType;
 import org.junit.Test;
@@ -138,21 +139,64 @@ public void selectTracks_createsSampleStreamsFromChildPeriods() throws Exception
     streams[0].readData(formatHolder, inputBuffer, FLAG_REQUIRE_FORMAT);
     streams[1].readData(formatHolder, inputBuffer, FLAG_REQUIRE_FORMAT);
 
-    FakeMediaPeriodWithSelectTracksPosition childMediaPeriod1 =
-        (FakeMediaPeriodWithSelectTracksPosition) mergingMediaPeriod.getChildPeriod(0);
+    FakeMediaPeriodWithSelectionParameters childMediaPeriod1 =
+        (FakeMediaPeriodWithSelectionParameters) mergingMediaPeriod.getChildPeriod(0);
     assertThat(childMediaPeriod1.selectTracksPositionUs).isEqualTo(0);
     assertThat(streams[0].readData(formatHolder, inputBuffer, /* readFlags= */ 0))
         .isEqualTo(C.RESULT_BUFFER_READ);
     assertThat(inputBuffer.timeUs).isEqualTo(123_000L);
 
-    FakeMediaPeriodWithSelectTracksPosition childMediaPeriod2 =
-        (FakeMediaPeriodWithSelectTracksPosition) mergingMediaPeriod.getChildPeriod(1);
+    FakeMediaPeriodWithSelectionParameters childMediaPeriod2 =
+        (FakeMediaPeriodWithSelectionParameters) mergingMediaPeriod.getChildPeriod(1);
     assertThat(childMediaPeriod2.selectTracksPositionUs).isEqualTo(3000L);
     assertThat(streams[1].readData(formatHolder, inputBuffer, /* readFlags= */ 0))
         .isEqualTo(C.RESULT_BUFFER_READ);
     assertThat(inputBuffer.timeUs).isEqualTo(456_000 - 3000);
   }
 
+  @Test
+  public void selectTracks_withSameArguments_forwardsEqualSelectionsToChildSources()
+      throws Exception {
+    MergingMediaPeriod mergingMediaPeriod =
+        prepareMergingPeriod(
+            new MergingPeriodDefinition(
+                /* timeOffsetUs= */ 0, /* singleSampleTimeUs= */ 0, childFormat11),
+            new MergingPeriodDefinition(
+                /* timeOffsetUs= */ 0, /* singleSampleTimeUs= */ 0, childFormat22));
+    FakeMediaPeriodWithSelectionParameters childMediaPeriod1 =
+        (FakeMediaPeriodWithSelectionParameters) mergingMediaPeriod.getChildPeriod(0);
+    FakeMediaPeriodWithSelectionParameters childMediaPeriod2 =
+        (FakeMediaPeriodWithSelectionParameters) mergingMediaPeriod.getChildPeriod(1);
+
+    TrackGroupArray mergedTrackGroups = mergingMediaPeriod.getTrackGroups();
+    ExoTrackSelection[] selectionArray =
+        new ExoTrackSelection[] {
+          new FixedTrackSelection(mergedTrackGroups.get(0), /* track= */ 0),
+          new FixedTrackSelection(mergedTrackGroups.get(1), /* track= */ 0)
+        };
+
+    mergingMediaPeriod.selectTracks(
+        selectionArray,
+        /* mayRetainStreamFlags= */ new boolean[2],
+        /* streams= */ new SampleStream[2],
+        /* streamResetFlags= */ new boolean[2],
+        /* positionUs= */ 0);
+    ExoTrackSelection firstSelectionChild1 = childMediaPeriod1.selectTracksSelections[0];
+    ExoTrackSelection firstSelectionChild2 = childMediaPeriod2.selectTracksSelections[1];
+
+    mergingMediaPeriod.selectTracks(
+        selectionArray,
+        /* mayRetainStreamFlags= */ new boolean[2],
+        /* streams= */ new SampleStream[2],
+        /* streamResetFlags= */ new boolean[2],
+        /* positionUs= */ 0);
+    ExoTrackSelection secondSelectionChild1 = childMediaPeriod1.selectTracksSelections[0];
+    ExoTrackSelection secondSelectionChild2 = childMediaPeriod2.selectTracksSelections[1];
+
+    assertThat(firstSelectionChild1).isEqualTo(secondSelectionChild1);
+    assertThat(firstSelectionChild2).isEqualTo(secondSelectionChild2);
+  }
+
   private MergingMediaPeriod prepareMergingPeriod(MergingPeriodDefinition... definitions)
       throws Exception {
     MediaPeriod[] mediaPeriods = new MediaPeriod[definitions.length];
@@ -165,7 +209,7 @@ private MergingMediaPeriod prepareMergingPeriod(MergingPeriodDefinition... defin
         trackGroups[j] = new TrackGroup(definition.formats[j]);
       }
       mediaPeriods[i] =
-          new FakeMediaPeriodWithSelectTracksPosition(
+          new FakeMediaPeriodWithSelectionParameters(
               new TrackGroupArray(trackGroups),
               new EventDispatcher()
                   .withParameters(
@@ -200,11 +244,12 @@ public void onContinueLoadingRequested(MediaPeriod source) {
     return mergingMediaPeriod;
   }
 
-  private static final class FakeMediaPeriodWithSelectTracksPosition extends FakeMediaPeriod {
+  private static final class FakeMediaPeriodWithSelectionParameters extends FakeMediaPeriod {
 
+    public @NullableType ExoTrackSelection[] selectTracksSelections;
     public long selectTracksPositionUs;
 
-    public FakeMediaPeriodWithSelectTracksPosition(
+    public FakeMediaPeriodWithSelectionParameters(
         TrackGroupArray trackGroupArray,
         EventDispatcher mediaSourceEventDispatcher,
         TrackDataFactory trackDataFactory) {
@@ -216,6 +261,7 @@ public FakeMediaPeriodWithSelectTracksPosition(
           DrmSessionManager.DRM_UNSUPPORTED,
           new DrmSessionEventListener.EventDispatcher(),
           /* deferOnPrepared= */ false);
+      selectTracksSelections = new ExoTrackSelection[trackGroupArray.length];
       selectTracksPositionUs = C.TIME_UNSET;
     }
 
@@ -226,6 +272,7 @@ public long selectTracks(
         @NullableType SampleStream[] streams,
         boolean[] streamResetFlags,
         long positionUs) {
+      selectTracksSelections = Arrays.copyOf(selections, selections.length);
       selectTracksPositionUs = positionUs;
       return super.selectTracks(
           selections, mayRetainStreamFlags, streams, streamResetFlags, positionUs);