Fix key status problems with EME polyfills.

Our EME polyfills give a key status with a Key ID of '00' (a single 0
byte).  This breaks the Player logic for restricted tracks since it
assumes that those are not playable.  When we get this Key ID, we should
treat the key status as a global status, not for that specific Key ID.

Closes #884
Closes #890

Change-Id: I392550227274fb321d2c223eb8d483a0a4733186

lib/player.js

@@ -2585,6 +2585,19 @@ shaka.Player.prototype.onKeyStatus_ = function(keyStatusMap) {
   var period = this.streamingEngine_.getCurrentPeriod();
   var tracksChanged = false;
 
+  // If EME is using a synthetic key, the only key is '00' (a single 0 byte).
+  // In this case, it is only used to report global success/failure.
+  // See note about old platforms in: https://goo.gl/KtQMja
+  var isGlobalStatus = Object.keys(keyStatusMap).length == 1 &&
+      Object.keys(keyStatusMap)[0] == '00';
+
+  if (isGlobalStatus) {
+    shaka.log.warning(
+        'Got a synthetic key status event, so we don\'t know the real key ' +
+        'statuses. If we don\'t have all the keys, you\'ll need to set ' +
+        'restrictions so we don\'t select those tracks.');
+  }
+
   period.variants.forEach(function(variant) {
     var streams = [];
     if (variant.audio) streams.push(variant.audio);
@@ -2596,7 +2609,7 @@ shaka.Player.prototype.onKeyStatus_ = function(keyStatusMap) {
       // Only update if we have a key ID for the stream.  If the key isn't
       // present, then we don't have that key and it should be restricted.
       if (stream.keyId) {
-        var keyStatus = keyStatusMap[stream.keyId];
+        var keyStatus = keyStatusMap[isGlobalStatus ? '00' : stream.keyId];
         variant.allowedByKeySystem =
             !!keyStatus && restrictedStatuses.indexOf(keyStatus) < 0;
       }

test/media/drm_engine_integration.js

@@ -216,8 +216,7 @@ describe('DrmEngine', function() {
             }
           }).then(function() {
             // Some platforms (notably 2017 Tizen TVs) do not fire key status
-            // events.  This is a temporary workaround for the test failure
-            // in https://github.com/google/shaka-player/issues/891
+            // events.
             var keyStatusTimeout = shaka.test.Util.delay(5);
             return Promise.race([keyStatusTimeout, keyStatusEventSeen]);
           }).then(function() {

test/player_unit.js

@@ -1909,6 +1909,66 @@ describe('Player', function() {
       }).catch(fail).then(done);
     });
 
+    it('doesn\'t remove when using synthetic key status', function(done) {
+      manifest = new shaka.test.ManifestGenerator()
+              .addPeriod(0)
+                .addVariant(0)
+                  .addVideo(1).keyId('abc')
+                .addVariant(2)
+                  .addVideo(3)
+              .build();
+
+      parser = new shaka.test.FakeManifestParser(manifest);
+      parserFactory = function() { return parser; };
+      player.load('', 0, parserFactory).then(function() {
+        // "initialize" the current period.
+        chooseStreams();
+        canSwitch();
+      }).then(function() {
+        expect(player.getVariantTracks().length).toBe(2);
+
+        // A synthetic key status contains a single key status with key '00'.
+        onKeyStatus({'00': 'usable'});
+
+        expect(player.getVariantTracks().length).toBe(2);
+      }).catch(fail).then(done);
+    });
+
+    it('removes all encrypted tracks for errors with synthetic key status',
+        function(done) {
+          manifest = new shaka.test.ManifestGenerator()
+                  .addPeriod(0)
+                    .addVariant(0)
+                      .addVideo(1).keyId('abc')
+                    .addVariant(2)
+                      .addVideo(3).keyId('xyz')
+                    .addVariant(4)
+                      .addVideo(5)
+                  .build();
+
+          parser = new shaka.test.FakeManifestParser(manifest);
+          parserFactory = function() { return parser; };
+          player.load('', 0, parserFactory)
+              .then(function() {
+                // "initialize" the current period.
+                chooseStreams();
+                canSwitch();
+              })
+              .then(function() {
+                expect(player.getVariantTracks().length).toBe(3);
+
+                // A synthetic key status contains a single key status with key
+                // '00'.
+                onKeyStatus({'00': 'internal-error'});
+
+                var tracks = player.getVariantTracks();
+                expect(tracks.length).toBe(1);
+                expect(tracks[0].id).toBe(4);
+              })
+              .catch(fail)
+              .then(done);
+        });
+
     it('removes if key system does not support codec', function(done) {
       manifest = new shaka.test.ManifestGenerator()
           .addPeriod(0)