fix: Dedupe DRM init data (shaka-project#3695)

Linear streams accumulate init data over time because the init data is pushed to
an array regardless of whether or not it already exists as part of the logic to
combine periods. This PR dedupes the init data based on keyId to help reduce
memory usage over extended playouts.

lib/media/drm_engine.js

@@ -1825,9 +1825,16 @@ shaka.media.DrmEngine = class {
         // audio adaptations, so we shouldn't have to worry about checking
         // robustness.
         if (drm1.keySystem == drm2.keySystem) {
+          /** @type {Array<shaka.extern.InitDataOverride>} */
           let initData = [];
           initData = initData.concat(drm1.initData || []);
           initData = initData.concat(drm2.initData || []);
+          initData = initData.filter((d, i) => {
+            return d.keyId === undefined || i === initData.findIndex((d2) => {
+              return d2.keyId === d.keyId;
+            });
+          });
+
           const keyIds = drm1.keyIds && drm2.keyIds ?
               new Set([...drm1.keyIds, ...drm2.keyIds]) :
               drm1.keyIds || drm2.keyIds;

test/media/drm_engine_unit.js

@@ -2152,6 +2152,50 @@ describe('DrmEngine', () => {
           [drmInfoAudio]);
       expect(returned).toEqual([drmInfoDesired]);
     });
+
+    it('dedupes the merged init data based on keyId matching', () => {
+      const serverCert = new Uint8Array(0);
+      const drmInfoVideo = {
+        keySystem: 'drm.abc',
+        licenseServerUri: 'http://abc.drm/license',
+        distinctiveIdentifierRequired: false,
+        persistentStateRequired: true,
+        videoRobustness: 'really_really_ridiculously_good',
+        serverCertificate: serverCert,
+        serverCertificateUri: '',
+        initData: [{keyId: 'v-init'}],
+        keyIds: new Set(['deadbeefdeadbeefdeadbeefdeadbeef']),
+      };
+      const drmInfoAudio = {
+        keySystem: 'drm.abc',
+        licenseServerUri: undefined,
+        distinctiveIdentifierRequired: true,
+        persistentStateRequired: false,
+        audioRobustness: 'good',
+        serverCertificate: undefined,
+        serverCertificateUri: '',
+        initData: [{keyId: 'v-init'}, {keyId: 'a-init'}],
+        keyIds: new Set(['eadbeefdeadbeefdeadbeefdeadbeefd']),
+      };
+      const drmInfoDesired = {
+        keySystem: 'drm.abc',
+        licenseServerUri: 'http://abc.drm/license',
+        distinctiveIdentifierRequired: true,
+        persistentStateRequired: true,
+        audioRobustness: 'good',
+        videoRobustness: 'really_really_ridiculously_good',
+        serverCertificate: serverCert,
+        serverCertificateUri: '',
+        initData: [{keyId: 'v-init'}, {keyId: 'a-init'}],
+        keyIds: new Set([
+          'deadbeefdeadbeefdeadbeefdeadbeef',
+          'eadbeefdeadbeefdeadbeefdeadbeefd',
+        ]),
+      };
+      const returned = shaka.media.DrmEngine.getCommonDrmInfos([drmInfoVideo],
+          [drmInfoAudio]);
+      expect(returned).toEqual([drmInfoDesired]);
+    });
   }); // describe('getCommonDrmInfos')
 
   describe('configure', () => {