Add useful DownloadRequest to MediaItem conversion method

PiperOrigin-RevId: 329722775

demos/main/src/main/java/com/google/android/exoplayer2/demo/PlayerActivity.java

@@ -550,17 +550,7 @@ public class PlayerActivity extends AppCompatActivity
       @Nullable
       DownloadRequest downloadRequest =
           downloadTracker.getDownloadRequest(checkNotNull(item.playbackProperties).uri);
-      if (downloadRequest != null) {
+      mediaItems.add(downloadRequest != null ? downloadRequest.toMediaItem() : item);
-        MediaItem mediaItem =
-            item.buildUpon()
-                .setStreamKeys(downloadRequest.streamKeys)
-                .setCustomCacheKey(downloadRequest.customCacheKey)
-                .setDrmKeySetId(downloadRequest.keySetId)
-                .build();
-        mediaItems.add(mediaItem);
-      } else {
-        mediaItems.add(item);
-      }
     }
     return mediaItems;
   }

library/core/src/main/java/com/google/android/exoplayer2/offline/DownloadHelper.java

@@ -448,14 +448,7 @@ public final class DownloadHelper {
       DataSource.Factory dataSourceFactory,
       @Nullable DrmSessionManager drmSessionManager) {
     return createMediaSourceInternal(
-        new MediaItem.Builder()
+        downloadRequest.toMediaItem(), dataSourceFactory, drmSessionManager);
-            .setUri(downloadRequest.uri)
-            .setCustomCacheKey(downloadRequest.customCacheKey)
-            .setMimeType(downloadRequest.mimeType)
-            .setStreamKeys(downloadRequest.streamKeys)
-            .build(),
-        dataSourceFactory,
-        drmSessionManager);
   }
 
   private final MediaItem.PlaybackProperties playbackProperties;

library/core/src/main/java/com/google/android/exoplayer2/offline/DownloadRequest.java

@@ -22,6 +22,7 @@ import android.os.Parcel;
 import android.os.Parcelable;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.MediaItem;
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.Util;
 import com.google.common.collect.ImmutableList;
@@ -220,6 +221,18 @@ public final class DownloadRequest implements Parcelable {
         newRequest.data);
   }
 
+  /** Returns a {@link MediaItem} for the content defined by the request. */
+  public MediaItem toMediaItem() {
+    return new MediaItem.Builder()
+        .setMediaId(id)
+        .setUri(uri)
+        .setCustomCacheKey(customCacheKey)
+        .setMimeType(mimeType)
+        .setStreamKeys(streamKeys)
+        .setDrmKeySetId(keySetId)
+        .build();
+  }
+
   @Override
   public String toString() {
     return mimeType + ":" + id;