Optimise bundling for `AdPlaybackState` using `AdPlaybackState.NONE`

Did not do this optimisation for `AdPlaybackState.AdGroup` as its length is zero for `AdPlaybackState` with no ads.

No need to pass default values while fetching keys, which we always set in `AdPlaybackState.AdGroup.toBundle()`.

PiperOrigin-RevId: 496995048

library/common/src/main/java/com/google/android/exoplayer2/source/ads/AdPlaybackState.java

@@ -508,9 +508,8 @@ public final class AdPlaybackState implements Bundleable {
     @SuppressWarnings("nullness:type.argument")
     private static AdGroup fromBundle(Bundle bundle) {
       long timeUs = bundle.getLong(keyForField(FIELD_TIME_US));
-      int count = bundle.getInt(keyForField(FIELD_COUNT), /* defaultValue= */ C.LENGTH_UNSET);
-      int originalCount =
-          bundle.getInt(keyForField(FIELD_ORIGINAL_COUNT), /* defaultValue= */ C.LENGTH_UNSET);
+      int count = bundle.getInt(keyForField(FIELD_COUNT));
+      int originalCount = bundle.getInt(keyForField(FIELD_ORIGINAL_COUNT));
       @Nullable
       ArrayList<@NullableType Uri> uriList = bundle.getParcelableArrayList(keyForField(FIELD_URIS));
       @Nullable
@@ -1153,10 +1152,18 @@ public final class AdPlaybackState implements Bundleable {
     for (AdGroup adGroup : adGroups) {
       adGroupBundleList.add(adGroup.toBundle());
     }
-    bundle.putParcelableArrayList(keyForField(FIELD_AD_GROUPS), adGroupBundleList);
-    bundle.putLong(keyForField(FIELD_AD_RESUME_POSITION_US), adResumePositionUs);
-    bundle.putLong(keyForField(FIELD_CONTENT_DURATION_US), contentDurationUs);
-    bundle.putInt(keyForField(FIELD_REMOVED_AD_GROUP_COUNT), removedAdGroupCount);
+    if (!adGroupBundleList.isEmpty()) {
+      bundle.putParcelableArrayList(keyForField(FIELD_AD_GROUPS), adGroupBundleList);
+    }
+    if (adResumePositionUs != NONE.adResumePositionUs) {
+      bundle.putLong(keyForField(FIELD_AD_RESUME_POSITION_US), adResumePositionUs);
+    }
+    if (contentDurationUs != NONE.contentDurationUs) {
+      bundle.putLong(keyForField(FIELD_CONTENT_DURATION_US), contentDurationUs);
+    }
+    if (removedAdGroupCount != NONE.removedAdGroupCount) {
+      bundle.putInt(keyForField(FIELD_REMOVED_AD_GROUP_COUNT), removedAdGroupCount);
+    }
     return bundle;
   }
 
@@ -1181,10 +1188,15 @@ public final class AdPlaybackState implements Bundleable {
       }
     }
     long adResumePositionUs =
-        bundle.getLong(keyForField(FIELD_AD_RESUME_POSITION_US), /* defaultValue= */ 0);
+        bundle.getLong(
+            keyForField(FIELD_AD_RESUME_POSITION_US), /* defaultValue= */ NONE.adResumePositionUs);
     long contentDurationUs =
-        bundle.getLong(keyForField(FIELD_CONTENT_DURATION_US), /* defaultValue= */ C.TIME_UNSET);
-    int removedAdGroupCount = bundle.getInt(keyForField(FIELD_REMOVED_AD_GROUP_COUNT));
+        bundle.getLong(
+            keyForField(FIELD_CONTENT_DURATION_US), /* defaultValue= */ NONE.contentDurationUs);
+    int removedAdGroupCount =
+        bundle.getInt(
+            keyForField(FIELD_REMOVED_AD_GROUP_COUNT),
+            /* defaultValue= */ NONE.removedAdGroupCount);
     return new AdPlaybackState(
         /* adsId= */ null, adGroups, adResumePositionUs, contentDurationUs, removedAdGroupCount);
   }

library/common/src/test/java/com/google/android/exoplayer2/source/ads/AdPlaybackStateTest.java

@@ -24,6 +24,7 @@ import static com.google.common.truth.Truth.assertThat;
 import static org.junit.Assert.fail;
 
 import android.net.Uri;
+import android.os.Bundle;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 import com.google.android.exoplayer2.C;
 import org.junit.Assert;
@@ -403,7 +404,44 @@ public class AdPlaybackStateTest {
   }
 
   @Test
-  public void roundTripViaBundle_yieldsEqualFieldsExceptAdsId() {
+  public void adPlaybackStateWithNoAds_checkValues() {
+    AdPlaybackState adPlaybackStateWithNoAds = AdPlaybackState.NONE;
+
+    // Please refrain from altering these values since doing so would cause issues with backwards
+    // compatibility.
+    assertThat(adPlaybackStateWithNoAds.adsId).isNull();
+    assertThat(adPlaybackStateWithNoAds.adGroupCount).isEqualTo(0);
+    assertThat(adPlaybackStateWithNoAds.adResumePositionUs).isEqualTo(0);
+    assertThat(adPlaybackStateWithNoAds.contentDurationUs).isEqualTo(C.TIME_UNSET);
+    assertThat(adPlaybackStateWithNoAds.removedAdGroupCount).isEqualTo(0);
+  }
+
+  @Test
+  public void adPlaybackStateWithNoAds_toBundleSkipsDefaultValues_fromBundleRestoresThem() {
+    AdPlaybackState adPlaybackStateWithNoAds = AdPlaybackState.NONE;
+
+    Bundle adPlaybackStateWithNoAdsBundle = adPlaybackStateWithNoAds.toBundle();
+
+    // check Bundle created above, contains no keys.
+    assertThat(adPlaybackStateWithNoAdsBundle.keySet()).isEmpty();
+
+    AdPlaybackState adPlaybackStateWithNoAdsFromBundle =
+        AdPlaybackState.CREATOR.fromBundle(adPlaybackStateWithNoAdsBundle);
+
+    // check object retrieved from adPlaybackStateWithNoAdsBundle is equal to AdPlaybackState.NONE
+    assertThat(adPlaybackStateWithNoAdsFromBundle.adsId).isEqualTo(adPlaybackStateWithNoAds.adsId);
+    assertThat(adPlaybackStateWithNoAdsFromBundle.adGroupCount)
+        .isEqualTo(adPlaybackStateWithNoAds.adGroupCount);
+    assertThat(adPlaybackStateWithNoAdsFromBundle.adResumePositionUs)
+        .isEqualTo(adPlaybackStateWithNoAds.adResumePositionUs);
+    assertThat(adPlaybackStateWithNoAdsFromBundle.contentDurationUs)
+        .isEqualTo(adPlaybackStateWithNoAds.contentDurationUs);
+    assertThat(adPlaybackStateWithNoAdsFromBundle.removedAdGroupCount)
+        .isEqualTo(adPlaybackStateWithNoAds.removedAdGroupCount);
+  }
+
+  @Test
+  public void createAdPlaybackState_roundTripViaBundle_yieldsEqualFieldsExceptAdsId() {
     AdPlaybackState originalState =
         new AdPlaybackState(TEST_ADS_ID, TEST_AD_GROUP_TIMES_US)
             .withRemovedAdGroupCount(1)