SPDY size utility method.

net/spdy/spdy_protocol.h

Index: net/spdy/spdy_protocol.h
diff --git a/net/spdy/spdy_protocol.h b/net/spdy/spdy_protocol.h
index cc73977a686fe02675fa09fec3bde6c96125bdc3..9ecd4e41dcc4b3fa3a6137c24b9042b75548ccf4 100644
--- a/net/spdy/spdy_protocol.h
+++ b/net/spdy/spdy_protocol.h
@@ -495,6 +495,10 @@ class NET_EXPORT_PRIVATE SpdyConstants {
 
   static size_t GetFrameMaximumSize(SpdyMajorVersion version);
 
+  // Returns the size of a header block size field. Valid only for SPDY
+  // versions <= 3.
+  static size_t GetSizeOfSizeField(SpdyMajorVersion version);
+
   static SpdyMajorVersion ParseMajorVersion(int version_number);
 
   static int SerializeMajorVersion(SpdyMajorVersion version);