Keep download in completed state if only metadata is updated

#minor-release

Issue: #8116
PiperOrigin-RevId: 342269114

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

@@ -666,21 +666,28 @@ public final class DownloadManager {
 
   /* package */ static Download mergeRequest(
       Download download, DownloadRequest request, int stopReason, long nowMs) {
+    DownloadRequest mergedRequest = download.request.copyWithMergedRequest(request);
+
     @Download.State int state = download.state;
     // Treat the merge as creating a new download if we're currently removing the existing one, or
-    // if the existing download is in a terminal state. Else treat the merge as updating the
-    // existing download.
+    // if the existing download has failed. Else treat the merge as updating the existing download.
     long startTimeMs =
-        state == STATE_REMOVING || download.isTerminalState() ? nowMs : download.startTimeMs;
-    if (state == STATE_REMOVING || state == STATE_RESTARTING) {
+        state == STATE_REMOVING || state == STATE_FAILED ? nowMs : download.startTimeMs;
+
+    if (state == STATE_COMPLETED
+        && mergedRequest.streamKeys.size() == download.request.streamKeys.size()) {
+      // A completed download is still completed if no new streams are added.
+      state = STATE_COMPLETED;
+    } else if (state == STATE_REMOVING || state == STATE_RESTARTING) {
       state = STATE_RESTARTING;
     } else if (stopReason != STOP_REASON_NONE) {
       state = STATE_STOPPED;
     } else {
       state = STATE_QUEUED;
     }
+
     return new Download(
-        download.request.copyWithMergedRequest(request),
+        mergedRequest,
         state,
         startTimeMs,
         /* updateTimeMs= */ nowMs,

library/core/src/test/java/com/google/android/exoplayer2/offline/DownloadManagerTest.java

@@ -635,22 +635,45 @@ public class DownloadManagerTest {
   }
 
   @Test
-  public void mergeRequest_completedWithStopReason_becomesStopped() {
-    DownloadRequest downloadRequest = createDownloadRequest(ID1);
+  public void mergeRequest_completedWithStopReason_mergesNewKeyAndBecomesStopped() {
+    StreamKey streamKey1 = new StreamKey(/* groupIndex= */ 0, /* trackIndex= */ 0);
+    StreamKey streamKey2 = new StreamKey(/* groupIndex= */ 0, /* trackIndex= */ 1);
+
+    DownloadRequest downloadRequest1 = createDownloadRequest(ID1, streamKey1);
     DownloadBuilder downloadBuilder =
-        new DownloadBuilder(downloadRequest)
+        new DownloadBuilder(downloadRequest1)
             .setState(Download.STATE_COMPLETED)
             .setStopReason(/* stopReason= */ 1);
     Download download = downloadBuilder.build();
 
+    DownloadRequest downloadRequest2 = createDownloadRequest(ID1, streamKey2);
     Download mergedDownload =
-        DownloadManager.mergeRequest(download, downloadRequest, download.stopReason, NOW_MS);
+        DownloadManager.mergeRequest(download, downloadRequest2, download.stopReason, NOW_MS);
 
     Download expectedDownload =
-        downloadBuilder.setStartTimeMs(NOW_MS).setState(Download.STATE_STOPPED).build();
+        downloadBuilder
+            .setStreamKeys(streamKey1, streamKey2)
+            .setState(Download.STATE_STOPPED)
+            .build();
     assertEqualIgnoringUpdateTime(mergedDownload, expectedDownload);
   }
 
+  @Test
+  public void mergeRequest_completed_staysCompleted() {
+    StreamKey streamKey = new StreamKey(/* groupIndex= */ 0, /* trackIndex= */ 0);
+
+    DownloadRequest downloadRequest1 = createDownloadRequest(ID1, streamKey);
+    DownloadBuilder downloadBuilder =
+        new DownloadBuilder(downloadRequest1).setState(Download.STATE_COMPLETED);
+    Download download = downloadBuilder.build();
+
+    DownloadRequest downloadRequest2 = createDownloadRequest(ID1, streamKey);
+    Download mergedDownload =
+        DownloadManager.mergeRequest(download, downloadRequest2, /* stopReason= */ 0, NOW_MS);
+
+    assertEqualIgnoringUpdateTime(mergedDownload, download);
+  }
+
   private void setupDownloadManager(int maxParallelDownloads) throws Exception {
     if (downloadManager != null) {
       releaseDownloadManager();