Wait for close(), but timeout after 1s

An improved workaround for https://crbug.com/690583 and #1093, on top
of PR #1168.

If we don't wait at all, we end up trying to use the same session ID
too quickly, which causes a playback failure.

Change-Id: I8c9d1a0f09432054b862e033b80b0c2f47739c74

lib/media/drm_engine.js

@@ -170,21 +170,23 @@ shaka.media.DrmEngine.prototype.destroy = function() {
   var Functional = shaka.util.Functional;
   this.destroyed_ = true;
 
-  // TODO: wait for sessions to close when destroying. Due to a bug in Chrome,
-  // sometimes the Promise returned by MediaKeySession#close never resolves.
-  // See #1093 and https://crbug.com/690583
+  var async = [];
+
+  // Wait for sessions to close when destroying.
   this.activeSessions_.forEach(function(activeSession) {
     // Ignore any errors when closing the sessions.  One such error would be
     // an invalid state error triggered by closing a session which has not
     // generated any key requests.
-    // Chrome sometimes returns |undefined|: https://crbug.com/690664
-    var p = activeSession.session.close() || Promise.resolve();
-    p = p.catch(Functional.noop);
+    var close = activeSession.session.close().catch(Functional.noop);
+    // Due to a bug in Chrome, sometimes the Promise returned by close()
+    // never resolves.  See #1093 and https://crbug.com/690583
+    var closeTimeout = new Promise(function(resolve) {
+      setTimeout(resolve, 1000);
+    });
+    async.push(Promise.race([close, closeTimeout]));
   });
   this.allSessionsLoaded_.reject();
 
-  var async = [];
-
   if (this.eventManager_)
     async.push(this.eventManager_.destroy());
 

test/offline/offline_integration.js

@@ -200,7 +200,15 @@ describe('Offline', /** @suppress {accessControls} */ function() {
           expect(session).toBeFalsy();
           return drmEngine.destroy();
         })
-        .catch(fail)
+        .catch(function(error) {
+          fail(error);
+
+          // Make sure we clean up the extra DrmEngine even if the Promise
+          // chain and test fail.
+          if (drmEngine) {
+            return drmEngine.destroy();
+          }
+        })
         .then(done);
   });