Enable round-tripping and updating of WebSourceBufferImpl timestamp offset

content/renderer/media/websourcebuffer_impl.h

Index: content/renderer/media/websourcebuffer_impl.h
diff --git a/content/renderer/media/websourcebuffer_impl.h b/content/renderer/media/websourcebuffer_impl.h
index f863d22b8aadd530e92276fc9103d468cc9db8ab..3cbbb2c7a359ba815f25a97e0e37e7f7f25f36d1 100644
--- a/content/renderer/media/websourcebuffer_impl.h
+++ b/content/renderer/media/websourcebuffer_impl.h
@@ -25,7 +25,13 @@ class WebSourceBufferImpl : public blink::WebSourceBuffer {
   // blink::WebSourceBuffer implementation.
   virtual bool setMode(AppendMode mode);
   virtual blink::WebTimeRanges buffered();
+  // TODO(wolenetz): Remove the void append(...) implementation once the bool
+  // append(...) is used by Blink. See http://crbug.com/249422.
   virtual void append(const unsigned char* data, unsigned length);
+  virtual bool append(
+      const unsigned char* data,
+      unsigned length,
+      double* new_timestamp_offset);
   virtual void abort();
   virtual void remove(double start, double end);
   virtual bool setTimestampOffset(double offset);