fix: Fix waiting for empty init datas

lib/media/drm_engine.js

@@ -700,9 +700,12 @@ shaka.media.DrmEngine = class {
           initDataOverride.initDataType, initDataOverride.initData);
     }
 
-    // If we have no sessions, we need to resolve the promise right now or else
-    // it will never get resolved.
-    if (!initDatas.length) {
+    // If there were no sessions to load, we need to resolve the promise right
+    // now or else it will never get resolved.
+    // We determine this by checking areAllSessionsLoaded_, rather than checking
+    // the number of initDatas, since the newInitData method can reject init
+    // datas in some circumstances.
+    if (this.areAllSessionsLoaded_()) {
       this.allSessionsLoaded_.resolve();
     }
 

test/media/drm_engine_unit.js

@@ -163,6 +163,22 @@ describe('DrmEngine', () => {
     });
   });
 
+
+  describe('createOrLoad', () => {
+    it('does not hang when given empty init data for offline', async () => {
+      tweakDrmInfos((drmInfos) => {
+        // An empty uint8array, like we make for fairplay content.
+        drmInfos[0].initData = [
+          {initData: new Uint8Array(0), initDataType: 'cenc', keyId: null},
+        ];
+      });
+      await drmEngine.initForStorage(
+          manifest.variants, /* usePersistentLicenses= */ false);
+      await drmEngine.createOrLoad();
+      expect(drmEngine.initialized()).toBe(true);
+    }, /* timeout= */ 1000);
+  });
+
   describe('init', () => {
     it('stops on first available key system', async () => {
       // Accept both drm.abc and drm.def.  Only one can be chosen.

test/test/externs/jasmine.js

@@ -467,8 +467,9 @@ var xdescribe = function(name, callback) {};
 /**
  * @param {string} name
  * @param {jasmine.Callback} callback
+ * @param {number=} timeout
  */
-var it = function(name, callback) {};
+var it = function(name, callback, timeout) {};
 
 
 /**