Update from https://crrev.com/316786

net/quic/quic_data_writer.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_QUIC_DATA_WRITER_H_
 #define NET_QUIC_QUIC_DATA_WRITER_H_
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "base/port.h"
 #include "base/strings/string_piece.h"
 #include "net/base/int128.h"
 #include "net/base/net_export.h"
 #include "net/quic/quic_protocol.h"
 
 namespace net {
 
 // This class provides facilities for packing QUIC data.
 //
 // The QuicDataWriter supports appending primitive values (int, string, etc)
-// to a frame instance.  The QuicDataWriter grows its internal memory buffer
-// dynamically to hold the sequence of primitive values.   The internal memory
-// buffer is exposed as the "data" of the QuicDataWriter.
+// to a frame instance.  The internal memory buffer is exposed as the "data"
+// of the QuicDataWriter.
 class NET_EXPORT_PRIVATE QuicDataWriter {
  public:
-  explicit QuicDataWriter(size_t length);
+  // Creates a QuicDataWriter where |buffer| is not owned.
+  QuicDataWriter(size_t size, char* buffer);
 
   ~QuicDataWriter();
 
   // Returns the size of the QuicDataWriter's data.
   size_t length() const { return length_; }
 
-  // Takes the buffer from the QuicDataWriter.
-  char* take();
+  // Retrieves the buffer from the QuicDataWriter without changing ownership.
+  char* data();
 
   // Methods for adding to the payload.  These values are appended to the end
   // of the QuicDataWriter payload. Note - binary integers are written in
   // host byte order (little endian) not network byte order (big endian).
   bool WriteUInt8(uint8 value);
   bool WriteUInt16(uint16 value);
   bool WriteUInt32(uint32 value);
   bool WriteUInt48(uint64 value);
   bool WriteUInt64(uint64 value);
   // Write unsigned floating point corresponding to the value. Large values are
@@ skipping 27 matching lines @@
   char* buffer_;
   size_t capacity_;  // Allocation size of payload (or -1 if buffer is const).
   size_t length_;    // Current length of the buffer.
 
   DISALLOW_COPY_AND_ASSIGN(QuicDataWriter);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_DATA_WRITER_H_