Fix return value for drmInfo() with src=

This shouldn't depend on the load state.

Issue #382

Change-Id: Ia601c79404e074ec080c923f239533a8d04f6e64

lib/player.js

@@ -2608,16 +2608,14 @@ shaka.Player.prototype.keySystem = function() {
 
 /**
  * Get the drm info used to initialize EME. If EME is not being used, this will
- * return |null|. If the player has not loaded content or is still loading
- * content, this will return |null|.
+ * return |null|. If the player is idle or has not initialized EME yet, this
+ * will return |null|.
  *
  * @return {?shaka.extern.DrmInfo}
  * @export
  */
 shaka.Player.prototype.drmInfo = function() {
-  return this.loadMode_ == shaka.Player.LoadMode.MEDIA_SOURCE ?
-         this.drmEngine_.getDrmInfo() :
-         null;
+  return this.drmEngine_ ? this.drmEngine_.getDrmInfo() : null;
 };