Don't request session sharing on CDMs that don't support it

Issue: #4834

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=214258163

RELEASENOTES.md

@@ -145,6 +145,9 @@
   looping ([#3829](https://github.com/google/ExoPlayer/issues/3829)).
 * Fix issue where `player.getCurrentTag()` throws an `IndexOutOfBoundsException`
   ([#4822](https://github.com/google/ExoPlayer/issues/4822)).
+* Fix bug preventing use of multiple key session support (`multiSession=true`)
+  for non-Widevine `DefaultDrmSessionManager` instances
+  ([#4834](https://github.com/google/ExoPlayer/issues/4834)).
 * IMA extension:
   * Refine the previous fix for empty ad groups to avoid discarding ad breaks
     unnecessarily ([#4030](https://github.com/google/ExoPlayer/issues/4030) and

library/core/src/main/java/com/google/android/exoplayer2/drm/DefaultDrmSessionManager.java

@@ -367,7 +367,11 @@ public class DefaultDrmSessionManager<T extends ExoMediaCrypto> implements DrmSe
     mode = MODE_PLAYBACK;
     sessions = new ArrayList<>();
     provisioningSessions = new ArrayList<>();
-    if (multiSession) {
+    if (multiSession && C.WIDEVINE_UUID.equals(uuid) && Util.SDK_INT >= 19) {
+      // TODO: Enabling session sharing probably doesn't do anything useful here. It would only be
+      // useful if DefaultDrmSession instances were aware of one another's state, which is not
+      // implemented. Or if custom renderers are being used that allow playback to proceed before
+      // keys, which seems unlikely to be true in practice.
       mediaDrm.setPropertyString("sessionSharing", "enable");
     }
     mediaDrm.setOnEventListener(new MediaDrmEventListener());