Add new HTTP/2 and HPACK decoder in net/http2/.

net/http2/decoder/payload_decoders/settings_payload_decoder.h

Index: net/http2/decoder/payload_decoders/settings_payload_decoder.h
diff --git a/net/http2/decoder/payload_decoders/settings_payload_decoder.h b/net/http2/decoder/payload_decoders/settings_payload_decoder.h
new file mode 100644
index 0000000000000000000000000000000000000000..40d3c367abad2ec615b5618a1d7aed2439f63d00
--- /dev/null
+++ b/net/http2/decoder/payload_decoders/settings_payload_decoder.h
@@ -0,0 +1,54 @@
+// 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 NET_HTTP2_DECODER_PAYLOAD_DECODERS_SETTINGS_PAYLOAD_DECODER_H_
+#define NET_HTTP2_DECODER_PAYLOAD_DECODERS_SETTINGS_PAYLOAD_DECODER_H_
+
+// Decodes the payload of a SETTINGS frame; for the RFC, see:
+//     http://httpwg.org/specs/rfc7540.html#SETTINGS
+
+#include "net/base/net_export.h"
+#include "net/http2/decoder/decode_buffer.h"
+#include "net/http2/decoder/decode_status.h"
+#include "net/http2/decoder/frame_decoder_state.h"
+#include "net/http2/http2_structures.h"
+
+namespace net {
+namespace test {
+class SettingsPayloadDecoderPeer;
+}  // namespace test
+
+class NET_EXPORT_PRIVATE SettingsPayloadDecoder {
+ public:
+  // Starts the decoding of a SETTINGS frame's payload, and completes it if
+  // the entire payload is in the provided decode buffer.
+  DecodeStatus StartDecodingPayload(FrameDecoderState* state, DecodeBuffer* db);
+
+  // Resumes decoding a SETTINGS frame that has been split across decode
+  // buffers.
+  DecodeStatus ResumeDecodingPayload(FrameDecoderState* state,
+                                     DecodeBuffer* db);
+
+ private:
+  friend class test::SettingsPayloadDecoderPeer;
+
+  // Decodes as many settings as are available in the decode buffer, starting at
+  // the first byte of one setting; if a single setting is split across buffers,
+  // ResumeDecodingPayload will handle starting from where the previous call
+  // left off, and then will call StartDecodingSettings.
+  DecodeStatus StartDecodingSettings(FrameDecoderState* state,
+                                     DecodeBuffer* db);
+
+  // Decoding a single SETTING returned a status other than kDecodeDone; this
+  // method just brings together the DCHECKs to reduce duplication.
+  DecodeStatus HandleNotDone(FrameDecoderState* state,
+                             DecodeBuffer* db,
+                             DecodeStatus status);
+
+  Http2SettingFields setting_fields_;
+};
+
+}  // namespace net
+
+#endif  // NET_HTTP2_DECODER_PAYLOAD_DECODERS_SETTINGS_PAYLOAD_DECODER_H_