Added OverwriteFlags method to SpdyFrameBuilder.

net/spdy/spdy_frame_builder.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/spdy/spdy_frame_builder.h"
 
 #include <limits>
 
 #include "base/logging.h"
 #include "net/spdy/spdy_framer.h"
@@ skipping 164 matching lines @@
                          sizeof(flags_length) - 1);
   } else {
     length_ = 0;
     success = WriteUInt16(length);
   }
 
   length_ = old_length;
   return success;
 }
 
+bool SpdyFrameBuilder::OverwriteFlags(const SpdyFramer& framer,
+                                      uint8 flags) {
+  DCHECK_LE(SPDY4, framer.protocol_version());
+  bool success = false;
+  const size_t old_length = length_;
+  // Flags are the fourth octet in the frame prefix.
+  length_ = 3;
+  success = WriteUInt8(flags);
+  length_ = old_length;
+  return success;
+}
+
 bool SpdyFrameBuilder::CanWrite(size_t length) const {
   if (length > kLengthMask) {
     DCHECK(false);
     return false;
   }
 
   if (length_ + length > capacity_) {
     DCHECK(false);
     return false;
   }
 
   return true;
 }
 
 }  // namespace net