Add HpackDecoder3, an adapter using HpackDecoder (in net/http2/hpack/decoder).

net/spdy/hpack/hpack_decoder3.h

Index: net/spdy/hpack/hpack_decoder3.h
diff --git a/net/spdy/hpack/hpack_decoder3.h b/net/spdy/hpack/hpack_decoder3.h
new file mode 100644
index 0000000000000000000000000000000000000000..6203dfd322b00fc23d9588a401f858b993bb0748
--- /dev/null
+++ b/net/spdy/hpack/hpack_decoder3.h
@@ -0,0 +1,112 @@
+// Copyright 2017 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_SPDY_HPACK_HPACK_DECODER3_H_
+#define NET_SPDY_HPACK_HPACK_DECODER3_H_
+
+// HpackDecoder3 implements HpackDecoderInterface, using Http2HpackDecoder to
+// decode HPACK blocks into HTTP/2 header lists as outlined in
+// http://tools.ietf.org/html/rfc7541.
+
+#include <stddef.h>
+
+#include <memory>
+
+#include "base/macros.h"
+#include "base/strings/string_piece.h"
+#include "net/base/net_export.h"
+#include "net/http2/hpack/decoder/hpack_decoder_listener.h"
+#include "net/http2/hpack/decoder/http2_hpack_decoder.h"
+#include "net/http2/hpack/hpack_string.h"
+#include "net/http2/hpack/http2_hpack_constants.h"
+#include "net/spdy/hpack/hpack_decoder_interface.h"
+#include "net/spdy/hpack/hpack_header_table.h"
+#include "net/spdy/spdy_header_block.h"
+#include "net/spdy/spdy_headers_handler_interface.h"
+
+namespace net {
+namespace test {
+class HpackDecoder3Peer;
+}  // namespace test
+
+class NET_EXPORT_PRIVATE HpackDecoder3 : public HpackDecoderInterface {
+ public:
+  friend test::HpackDecoder3Peer;
+  HpackDecoder3();
+  ~HpackDecoder3() override;
+
+  // Override the HpackDecoderInterface methods:
+
+  void ApplyHeaderTableSizeSetting(size_t size_setting) override;
+  void HandleControlFrameHeadersStart(
+      SpdyHeadersHandlerInterface* handler) override;
+  bool HandleControlFrameHeadersData(const char* headers_data,
+                                     size_t headers_data_length) override;
+  bool HandleControlFrameHeadersComplete(size_t* compressed_len) override;
+  const SpdyHeaderBlock& decoded_block() const override;
+  void SetHeaderTableDebugVisitor(
+      std::unique_ptr<HpackHeaderTable::DebugVisitorInterface> visitor)
+      override;
+  void set_max_decode_buffer_size_bytes(
+      size_t max_decode_buffer_size_bytes) override;
+
+ private:
+  class NET_EXPORT_PRIVATE ListenerAdapter : public HpackDecoderListener {
+   public:
+    ListenerAdapter();
+    ~ListenerAdapter() override;
+
+    // If a SpdyHeadersHandlerInterface is provided, the decoder will emit
+    // headers to it rather than accumulating them in a SpdyHeaderBlock.
+    // Does not take ownership of the handler, but does use the pointer until
+    // the current HPACK block is completely decoded.
+    void set_handler(SpdyHeadersHandlerInterface* handler);
+    const SpdyHeaderBlock& decoded_block() const { return decoded_block_; }
+
+    // Override the HpackDecoderListener methods:
+
+    void OnHeaderListStart() override;
+    void OnHeader(HpackEntryType entry_type,
+                  const HpackString& name,
+                  const HpackString& value) override;
+    void OnHeaderListEnd() override;
+    void OnHeaderErrorDetected(base::StringPiece error_message) override;
+
+   private:
+    // If the caller doesn't provide a handler, the header list is stored in
+    // this SpdyHeaderBlock.
+    SpdyHeaderBlock decoded_block_;
+
+    // If non-NULL, handles decoded headers. Not owned.
+    SpdyHeadersHandlerInterface* handler_;
+
+    // Total bytes of the name and value strings in the current HPACK block.
+    size_t total_uncompressed_bytes_;
+  };
+
+  // Converts calls to HpackDecoderListener into calls to
+  // SpdyHeadersHandlerInterface.
+  ListenerAdapter listener_adapter_;
+
+  // The actual decoder.
+  Http2HpackDecoder hpack_decoder_;
+
+  // Total bytes that have been received as input (i.e. HPACK encoded)
+  // in the current HPACK block.
+  size_t total_hpack_bytes_;
+
+  // How much encoded data this decoder is willing to buffer.
+  size_t max_decode_buffer_size_bytes_;
+
+  // Flag to keep track of having seen the header block start. Needed at the
+  // moment because HandleControlFrameHeadersStart won't be called if a handler
+  // is not being provided by the caller.
+  bool header_block_started_;
+
+  DISALLOW_COPY_AND_ASSIGN(HpackDecoder3);
+};
+
+}  // namespace net
+
+#endif  // NET_SPDY_HPACK_HPACK_DECODER3_H_