Update window-extensions-release.aar to include animationBackgroundColor

This is to make sure the WM Jetpack call to setAnimationBackgroundColor
won't throw exception.

Bug: 263047900
Test: atest WMJetpackUnitTests:WindowExtensionsTest
Change-Id: I93bb66f2680145cbb7b4d975ae397c5c826fa36a

libs/WindowManager/Jetpack/tests/unittest/src/androidx/window/extensions/WindowExtensionsTest.java

@@ -22,6 +22,7 @@ import android.platform.test.annotations.Presubmit;
 
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 import androidx.test.filters.SmallTest;
+import androidx.window.extensions.embedding.SplitAttributes;
 
 import org.junit.Before;
 import org.junit.Test;
@@ -53,4 +54,15 @@ public class WindowExtensionsTest {
     public void testGetActivityEmbeddingComponent() {
         assertThat(mExtensions.getActivityEmbeddingComponent()).isNotNull();
     }
+
+    @Test
+    public void testSplitAttributes_default() {
+        // Make sure the default value in the extensions aar.
+        final SplitAttributes splitAttributes = new SplitAttributes.Builder().build();
+        assertThat(splitAttributes.getLayoutDirection())
+                .isEqualTo(SplitAttributes.LayoutDirection.LOCALE);
+        assertThat(splitAttributes.getSplitType())
+                .isEqualTo(new SplitAttributes.SplitType.RatioSplitType(0.5f));
+        assertThat(splitAttributes.getAnimationBackgroundColor()).isEqualTo(0);
+    }
 }