Add QUIC v40 which will be used to include changes:

net/quic/core/quic_versions.h

 // 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.
 
 #ifndef NET_QUIC_CORE_QUIC_VERSIONS_H_
 #define NET_QUIC_CORE_QUIC_VERSIONS_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 15 matching lines @@
 
   QUIC_VERSION_35 = 35,  // Allows endpoints to independently set stream limit.
   QUIC_VERSION_36 = 36,  // Add support to force HOL blocking.
   QUIC_VERSION_37 = 37,  // Add perspective into null encryption.
   QUIC_VERSION_38 = 38,  // PADDING frame is a 1-byte frame with type 0x00.
                          // Respect NSTP connection option.
   QUIC_VERSION_39 = 39,  // Integers and floating numbers are written in big
                          // endian. Dot not ack acks. Send a connection level
                          // WINDOW_UPDATE every 20 sent packets which do not
                          // contain retransmittable frames.
+  QUIC_VERSION_40 = 40,  // Initial packet number is randomly chosen from
+                         // [0:2^31], WINDOW_UPDATE for connection flow control
+                         // advertises value in 1024-byte units, WINDOW_UPDATE
+                         // splits into MAX_DATA and MAX_STREAM_DATA, BLOCKED
+                         // frame split into BLOCKED and STREAM_BLOCKED frames
 
   // IMPORTANT: if you are adding to this list, follow the instructions at
   // http://sites/quic/adding-and-removing-versions
 };
 
 // This vector contains QUIC versions which we currently support.
 // This should be ordered such that the highest supported version is the first
 // element, with subsequent elements in descending order (versions can be
 // skipped as necessary).
 //
 // IMPORTANT: if you are adding to this list, follow the instructions at
 // http://sites/quic/adding-and-removing-versions
 static const QuicVersion kSupportedQuicVersions[] = {
-    QUIC_VERSION_39, QUIC_VERSION_38, QUIC_VERSION_37, QUIC_VERSION_36,
-    QUIC_VERSION_35};
+    QUIC_VERSION_40, QUIC_VERSION_39, QUIC_VERSION_38,
+    QUIC_VERSION_37, QUIC_VERSION_36, QUIC_VERSION_35};
 
 typedef std::vector<QuicVersion> QuicVersionVector;
 
 // Returns a vector of QUIC versions in kSupportedQuicVersions.
 QUIC_EXPORT_PRIVATE QuicVersionVector AllSupportedVersions();
 
 // Returns a vector of QUIC versions from kSupportedQuicVersions which exclude
 // any versions which are disabled by flags.
 QUIC_EXPORT_PRIVATE QuicVersionVector CurrentSupportedVersions();
 
@@ skipping 22 matching lines @@
 QUIC_EXPORT_PRIVATE std::string QuicVersionToString(const QuicVersion version);
 
 // Returns comma separated list of string representations of QuicVersion enum
 // values in the supplied |versions| vector.
 QUIC_EXPORT_PRIVATE std::string QuicVersionVectorToString(
     const QuicVersionVector& versions);
 
 }  // namespace net
 
 #endif  // NET_QUIC_CORE_QUIC_VERSIONS_H_