Improve DownloadNotificationHelper

- Remove completed downloads from progress notification.
- Treat restarting as a downloading, When there are both
remove and download tasks ongoing, we prefer to show a
download notification to a remove one. A restarting task
encapsulates is basically a (remove+download) task. Given
our preference, we should treat it as a download rather
than as a removal.

PiperOrigin-RevId: 242867228

library/ui/src/main/java/com/google/android/exoplayer2/ui/DownloadNotificationHelper.java

@@ -64,13 +64,12 @@ public final class DownloadNotificationHelper {
     boolean haveDownloadTasks = false;
     boolean haveDownloadTasks = false;
     boolean haveRemoveTasks = false;
     boolean haveRemoveTasks = false;
     for (Download download : downloads) {
     for (Download download : downloads) {
-      if (download.state == Download.STATE_REMOVING
-          || download.state == Download.STATE_RESTARTING) {
+      if (download.state == Download.STATE_REMOVING) {
         haveRemoveTasks = true;
         haveRemoveTasks = true;
         continue;
         continue;
       }
       }
-      if (download.state != Download.STATE_DOWNLOADING
-          && download.state != Download.STATE_COMPLETED) {
+      if (download.state != Download.STATE_RESTARTING
+          && download.state != Download.STATE_DOWNLOADING) {
         continue;
         continue;
       }
       }
       haveDownloadTasks = true;
       haveDownloadTasks = true;