Move header-ordering validation from hpack decoder to header validator.

net/spdy/hpack/hpack_decoder.h

Index: net/spdy/hpack/hpack_decoder.h
diff --git a/net/spdy/hpack/hpack_decoder.h b/net/spdy/hpack/hpack_decoder.h
index 2d65719bf461498b4d266c1efccbbb2aef7d035c..07cfb3c795b379a05c3ff07b098d77cf380cbf41 100644
--- a/net/spdy/hpack/hpack_decoder.h
+++ b/net/spdy/hpack/hpack_decoder.h
@@ -111,9 +111,6 @@ class NET_EXPORT_PRIVATE HpackDecoder {
   SpdyHeadersHandlerInterface* handler_;
   size_t total_header_bytes_;
 
-  // Flag to keep track of having seen a regular header field.
-  bool regular_header_seen_;
-
   // Flag to keep track of having seen the header block start.
   bool header_block_started_;