Deliver change notifications to SourceBuffer track lists.

third_party/WebKit/LayoutTests/media/avtrack/video-track-selected.html

Index: third_party/WebKit/LayoutTests/media/avtrack/video-track-selected.html
diff --git a/third_party/WebKit/LayoutTests/media/avtrack/video-track-selected.html b/third_party/WebKit/LayoutTests/media/avtrack/video-track-selected.html
index 32254ddac96b8fb63c02aa5d99e83005f247525c..072ccf88836f873d031fa3453342f58a964468e5 100644
--- a/third_party/WebKit/LayoutTests/media/avtrack/video-track-selected.html
+++ b/third_party/WebKit/LayoutTests/media/avtrack/video-track-selected.html
@@ -23,9 +23,9 @@
                     assert_equals(e.videoTracks.selectedIndex, -1, "videoTracks.selectedIndex (first setter)");
                     assert_false(e.videoTracks[0].selected, "videoTrack.selected (first setter)");
 
-                    e.videoTracks.onchange = t.unreached_func("setting selected to false fired change event");

[servolk, 2016/08/22 17:37:36]

Note: I'm changing this intentionally. It looks like the current check is
incorrect, the change event must be fired even when the video track is
deselected. According to
https://www.w3.org/TR/html/single-page.html#audiotracklist-and-videotracklist...:
...
Whenever a track in a VideoTrackList that was previously not selected is
selected, and whenever the selected track in a VideoTrackList is unselected
without a new track being selected in its stead, the user agent must queue a
task to fire a simple event named change at the VideoTrackList object.
...

-                    setTimeout(t.step_func(function()
+                    e.videoTracks.onchange = t.step_func(function()
                     {
+                        assert_false(e.videoTracks[0].selected, "videoTrack.selected (first setter)");
                         e.videoTracks[0].selected = true;
                         assert_equals(e.videoTracks.selectedIndex, 0, "videoTracks.selectedIndex (second setter)");
                         assert_true(e.videoTracks[0].selected, "videoTrack.selected (second setter)");
@@ -36,7 +36,7 @@
                             assert_true(e.videoTracks[0].selected, "videoTrack.selected (change event)");
                             t.done();
                         });
-                    }), 0);
+                    });
                 });
             }, "VideoTrackList track change");
         </script>