diff --git a/http2/hpack/decoder/hpack_decoder_string_buffer.h b/http2/hpack/decoder/hpack_decoder_string_buffer.h
new file mode 100644
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+++ b/http2/hpack/decoder/hpack_decoder_string_buffer.h
@@ -0,0 +1,102 @@
+// Copyright 2016 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 QUICHE_HTTP2_HPACK_DECODER_HPACK_DECODER_STRING_BUFFER_H_
+#define QUICHE_HTTP2_HPACK_DECODER_HPACK_DECODER_STRING_BUFFER_H_
+
+// HpackDecoderStringBuffer helps an HPACK decoder to avoid copies of a string
+// literal (name or value) except when necessary (e.g. when split across two
+// or more HPACK block fragments).
+
+#include <stddef.h>
+
+#include <ostream>
+
+#include "net/third_party/quiche/src/http2/hpack/huffman/hpack_huffman_decoder.h"
+#include "net/third_party/quiche/src/http2/platform/api/http2_export.h"
+#include "net/third_party/quiche/src/http2/platform/api/http2_string.h"
+#include "net/third_party/quiche/src/http2/platform/api/http2_string_piece.h"
+
+namespace http2 {
+
+class HTTP2_EXPORT_PRIVATE HpackDecoderStringBuffer {
+ public:
+  enum class State : uint8_t { RESET, COLLECTING, COMPLETE };
+  enum class Backing : uint8_t { RESET, UNBUFFERED, BUFFERED, STATIC };
+
+  HpackDecoderStringBuffer();
+  ~HpackDecoderStringBuffer();
+
+  HpackDecoderStringBuffer(const HpackDecoderStringBuffer&) = delete;
+  HpackDecoderStringBuffer& operator=(const HpackDecoderStringBuffer&) = delete;
+
+  void Reset();
+  void Set(Http2StringPiece value, bool is_static);
+
+  // Note that for Huffman encoded strings the length of the string after
+  // decoding may be larger (expected), the same or even smaller; the latter
+  // are unlikely, but possible if the encoder makes odd choices.
+  void OnStart(bool huffman_encoded, size_t len);
+  bool OnData(const char* data, size_t len);
+  bool OnEnd();
+  void BufferStringIfUnbuffered();
+  bool IsBuffered() const;
+  size_t BufferedLength() const;
+
+  // Accessors for the completely collected string (i.e. Set or OnEnd has just
+  // been called, and no reset of the state has occurred).
+
+  // Returns a Http2StringPiece pointing to the backing store for the string,
+  // either the internal buffer or the original transport buffer (e.g. for a
+  // literal value that wasn't Huffman encoded, and that wasn't split across
+  // transport buffers).
+  Http2StringPiece str() const;
+
+  // Returns the completely collected string by value, using std::move in an
+  // effort to avoid unnecessary copies. ReleaseString() must not be called
+  // unless the string has been buffered (to avoid forcing a potentially
+  // unnecessary copy). ReleaseString() also resets the instance so that it can
+  // be used to collect another string.
+  Http2String ReleaseString();
+
+  State state_for_testing() const { return state_; }
+  Backing backing_for_testing() const { return backing_; }
+  void OutputDebugStringTo(std::ostream& out) const;
+
+  // Returns the estimate of dynamically allocated memory in bytes.
+  size_t EstimateMemoryUsage() const;
+
+ private:
+  // Storage for the string being buffered, if buffering is necessary
+  // (e.g. if Huffman encoded, buffer_ is storage for the decoded string).
+  Http2String buffer_;
+
+  // The Http2StringPiece to be returned by HpackDecoderStringBuffer::str(). If
+  // a string has been collected, but not buffered, value_ points to that
+  // string.
+  Http2StringPiece value_;
+
+  // The decoder to use if the string is Huffman encoded.
+  HpackHuffmanDecoder decoder_;
+
+  // Count of bytes not yet passed to OnData.
+  size_t remaining_len_;
+
+  // Is the HPACK string Huffman encoded?
+  bool is_huffman_encoded_;
+
+  // State of the string decoding process.
+  State state_;
+
+  // Where is the string stored?
+  Backing backing_;
+};
+
+HTTP2_EXPORT_PRIVATE std::ostream& operator<<(
+    std::ostream& out,
+    const HpackDecoderStringBuffer& v);
+
+}  // namespace http2
+
+#endif  // QUICHE_HTTP2_HPACK_DECODER_HPACK_DECODER_STRING_BUFFER_H_