Enable round-tripping and updating of SourceBuffer timestamp offset

Source/modules/mediasource/WebKitSourceBuffer.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 118 matching lines @@
     //    an InvalidStateError exception and abort these steps.
     if (throwExceptionIfRemoved(isRemoved(), exceptionState))
         return;
 
     // 5. If the readyState attribute of media source is in the "ended" state then run the following steps:
     // 5.1. Set the readyState attribute of media source to "open"
     // 5.2. Queue a task to fire a simple event named sourceopen at media source.
     m_source->openIfInEndedState();
 
     // Steps 6 & beyond are handled by m_webSourceBuffer.
-    m_webSourceBuffer->append(data->data(), data->length());
+
+    // Use null for |timestampOffset| parameter because the prefixed API does not allow appends
+    // to update timestampOffset.
+    m_webSourceBuffer->append(data->data(), data->length(), 0);
 }
 
 void WebKitSourceBuffer::abort(ExceptionState& exceptionState)
 {
     // Section 3.2 abort() method steps.
     // 1. If this object has been removed from the sourceBuffers attribute of the parent media source
     //    then throw an InvalidStateError exception and abort these steps.
     // 2. If the readyState attribute of the parent media source is not in the "open" state
     //    then throw an InvalidStateError exception and abort these steps.
     if (throwExceptionIfRemoved(isRemoved(), exceptionState))
@@ skipping 20 matching lines @@
 {
     return !m_source;
 }
 
 void WebKitSourceBuffer::trace(Visitor* visitor)
 {
     visitor->trace(m_source);
 }
 
 } // namespace WebCore