[SPDY] Incorporate latest framing changes from HTTP2 into SPDY 4 as SPDY 4a2.

net/spdy/spdy_frame_builder.h

Index: net/spdy/spdy_frame_builder.h
diff --git a/net/spdy/spdy_frame_builder.h b/net/spdy/spdy_frame_builder.h
index 7f9b3b1b975b43c365b56b7d22a516d817068445..825254de416aa0674ddf4bbacfb575bab60fcb89 100644
--- a/net/spdy/spdy_frame_builder.h
+++ b/net/spdy/spdy_frame_builder.h
@@ -50,6 +50,7 @@ class NET_EXPORT_PRIVATE SpdyFrameBuilder {
   // Populates this frame with a SPDY control frame header using
   // version-specific information from the |framer| and length information from
   // capacity_. The given type must be a control frame type.
+  // Used only for SPDY versions <4.
   bool WriteControlFrameHeader(const SpdyFramer& framer,
                                SpdyFrameType type,
                                uint8 flags);
@@ -60,6 +61,15 @@ class NET_EXPORT_PRIVATE SpdyFrameBuilder {
                             SpdyStreamId stream_id,
                             SpdyDataFlags flags);
 
+  // Populates this frame with a SPDY4/HTTP2 frame prefix using
+  // version-specific information from the |framer| and length information from
+  // capacity_. The given type must be a control frame type.
+  // Used only for SPDY versions >=4.
+  bool WriteFramePrefix(const SpdyFramer& framer,
+                        SpdyFrameType type,
+                        uint8 flags,
+                        SpdyStreamId stream_id);
+
   // Takes the buffer from the SpdyFrameBuilder.
   SpdyFrame* take() {
     SpdyFrame* rv = new SpdyFrame(buffer_.release(), length_, true);