Switch from a DataPipe per DecoderBuffer to a single one.

media/base/decoder_buffer.h

Index: media/base/decoder_buffer.h
diff --git a/media/base/decoder_buffer.h b/media/base/decoder_buffer.h
index 4f8ec69f5b4600b3e1d0de0b9940a194990b2740..665313ddcc1a698a23452c706355c80ed99f98d3 100644
--- a/media/base/decoder_buffer.h
+++ b/media/base/decoder_buffer.h
@@ -169,6 +169,9 @@ class MEDIA_EXPORT DecoderBuffer
   // Returns a human-readable string describing |*this|.
   std::string AsHumanReadableString();
 
+  // Replaces any existing side data with data copied from |side_data|.
+  void CopySideDataFrom(const uint8* side_data, int side_data_size);
+
  protected:
   friend class base::RefCountedThreadSafe<DecoderBuffer>;