Do the codec string parsing for MSE in media, instead of Blink

public/platform/WebMediaSource.h

 /*
  * Copyright (C) 2013 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 35 matching lines @@
         AddStatusReachedIdLimit
     };
 
     enum EndOfStreamStatus {
         EndOfStreamStatusNoError,
         EndOfStreamStatusNetworkError,
         EndOfStreamStatusDecodeError,
     };
 
     virtual ~WebMediaSource() { }
-    virtual AddStatus addSourceBuffer(const WebString& type, const WebVector<WebString>& codecs, WebSourceBuffer**) = 0;
+    virtual AddStatus addSourceBuffer(const WebString& type, const WebString& codecs, WebSourceBuffer**) = 0;
     virtual double duration() = 0;
     virtual void setDuration(double) = 0;
     virtual void markEndOfStream(EndOfStreamStatus) = 0;
     virtual void unmarkEndOfStream() = 0;
 };
 
 } // namespace blink
 
 #endif