Hide internal DownloadManager states

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=188481259

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

@@ -607,8 +607,7 @@ public class DownloadManagerTest {
     }
 
     private FakeDownloadAction assertStopped() {
-      assertState(DownloadState.STATE_STOPPING);
-      return assertState(DownloadState.STATE_WAITING);
+      return assertState(DownloadState.STATE_QUEUED);
     }
 
     private FakeDownloadAction assertState(@State int expectedState) {

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

@@ -67,12 +67,16 @@ public final class DownloadNotificationUtil {
     int titleStringId = getTitleStringId(downloadState);
     notificationBuilder.setContentTitle(context.getResources().getString(titleStringId));
 
-    if (downloadState.isRunning()) {
+    if (downloadState.state == DownloadState.STATE_STARTED) {
       notificationBuilder.setOngoing(true);
       float percentage = downloadState.downloadPercentage;
       boolean indeterminate = Float.isNaN(percentage);
       notificationBuilder.setProgress(100, indeterminate ? 0 : (int) percentage, indeterminate);
     }
+    if (Util.SDK_INT >= 17) {
+      // Hide timestamp on the notification while download progresses.
+      notificationBuilder.setShowWhen(downloadState.state != DownloadState.STATE_STARTED);
+    }
 
     if (downloadState.error != null && errorMessageProvider != null) {
       message = errorMessageProvider.getErrorMessage(downloadState.error).second;
@@ -90,12 +94,10 @@ public final class DownloadNotificationUtil {
   private static int getTitleStringId(DownloadState downloadState) {
     int titleStringId;
     switch (downloadState.state) {
-      case DownloadState.STATE_WAITING:
+      case DownloadState.STATE_QUEUED:
         titleStringId = R.string.exo_download_queued;
         break;
       case DownloadState.STATE_STARTED:
-      case DownloadState.STATE_STOPPING:
-      case DownloadState.STATE_CANCELING:
         titleStringId = R.string.exo_downloading;
         break;
       case DownloadState.STATE_ENDED: