MSE: Start letting SourceBuffer begin to do initialization segment received algorithm

LayoutTests/http/tests/media/media-source/mediasource-util.js

 (function(window) {
     // Set the testharness.js timeout to 120 seconds so that it is higher than
     // the LayoutTest timeout. This prevents testharness.js from prematurely
     // terminating tests and allows the LayoutTest runner to control when to
     // timeout the test.
     setup({ explicit_timeout: 120000 });
 
     var SEGMENT_INFO_LIST = [
         {
             url: '/media/resources/media-source/webm/test.webm',
@@ skipping 342 matching lines @@
                 oldTestDone();
             };
 
             openMediaSource_(test, mediaTag, function(mediaSource)
             {
                 testFunction(test, mediaTag, mediaSource);
             });
         }, description, options);
     };
 
-    window['mediasource_testafterdataloaded'] = function(testFunction, description, options)
+    window['mediasource_testafterdataloaded_internal'] = function(testFunction, description, failOnMediaElementError, options)
     {
         mediasource_test(function(test, mediaElement, mediaSource)
         {
             var segmentInfo = MediaSourceUtil.SEGMENT_INFO;
 
             if (!segmentInfo) {
                 assert_unreached("No segment info compatible with this MediaSource implementation.");
                 return;
             }
 
-            test.failOnEvent(mediaElement, 'error');
+            if (failOnMediaElementError)
+                test.failOnEvent(mediaElement, 'error');
 
             var sourceBuffer = mediaSource.addSourceBuffer(segmentInfo.type);
             MediaSourceUtil.loadBinaryData(test, segmentInfo.url, function(mediaData)
             {
                 testFunction(test, mediaElement, mediaSource, segmentInfo, sourceBuffer, mediaData);
             });
         }, description, options);
-    }
+    };
+
+    window['mediasource_testafterdataloaded'] = function(testFunction, description, options)
+    {
+        mediasource_testafterdataloaded_internal(testFunction, description, true, options);
+    };
+
+    window['mediasource_testafterdataloaded_nofailonerror'] = function(testFunction, description, options)
+    {
+        mediasource_testafterdataloaded_internal(testFunction, description, false, options);
+    };
 
     function timeRangesToString(ranges)
     {
         var s = "{";
         for (var i = 0; i < ranges.length; ++i) {
             s += " [" + ranges.start(i).toFixed(3) + ", " + ranges.end(i).toFixed(3) + ")";
         }
         return s + " }";
     }
 
     window['assertBufferedEquals'] = function(obj, expected, description)
     {
         var actual = timeRangesToString(obj.buffered);
         assert_equals(actual, expected, description);
     };
 
 })(window);