diff --git a/http2/decoder/http2_frame_decoder.h b/http2/decoder/http2_frame_decoder.h
new file mode 100644
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--- /dev/null
+++ b/http2/decoder/http2_frame_decoder.h
@@ -0,0 +1,205 @@
+// 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_DECODER_HTTP2_FRAME_DECODER_H_
+#define QUICHE_HTTP2_DECODER_HTTP2_FRAME_DECODER_H_
+
+// Http2FrameDecoder decodes the available input until it reaches the end of
+// the input or it reaches the end of the first frame in the input.
+// Note that Http2FrameDecoder does only minimal validation; for example,
+// stream ids are not checked, nor is the sequence of frames such as
+// CONTINUATION frame placement.
+//
+// Http2FrameDecoder enters state kError once it has called the listener's
+// OnFrameSizeError or OnPaddingTooLong methods, and at this time has no
+// provision for leaving that state. While the HTTP/2 spec (RFC7540) allows
+// for some such errors to be considered as just stream errors in some cases,
+// this implementation treats them all as connection errors.
+
+#include <stddef.h>
+
+#include <cstdint>
+
+#include "base/logging.h"
+#include "net/third_party/quiche/src/http2/decoder/decode_buffer.h"
+#include "net/third_party/quiche/src/http2/decoder/decode_status.h"
+#include "net/third_party/quiche/src/http2/decoder/frame_decoder_state.h"
+#include "net/third_party/quiche/src/http2/decoder/http2_frame_decoder_listener.h"
+#include "net/third_party/quiche/src/http2/decoder/payload_decoders/altsvc_payload_decoder.h"
+#include "net/third_party/quiche/src/http2/decoder/payload_decoders/continuation_payload_decoder.h"
+#include "net/third_party/quiche/src/http2/decoder/payload_decoders/data_payload_decoder.h"
+#include "net/third_party/quiche/src/http2/decoder/payload_decoders/goaway_payload_decoder.h"
+#include "net/third_party/quiche/src/http2/decoder/payload_decoders/headers_payload_decoder.h"
+#include "net/third_party/quiche/src/http2/decoder/payload_decoders/ping_payload_decoder.h"
+#include "net/third_party/quiche/src/http2/decoder/payload_decoders/priority_payload_decoder.h"
+#include "net/third_party/quiche/src/http2/decoder/payload_decoders/push_promise_payload_decoder.h"
+#include "net/third_party/quiche/src/http2/decoder/payload_decoders/rst_stream_payload_decoder.h"
+#include "net/third_party/quiche/src/http2/decoder/payload_decoders/settings_payload_decoder.h"
+#include "net/third_party/quiche/src/http2/decoder/payload_decoders/unknown_payload_decoder.h"
+#include "net/third_party/quiche/src/http2/decoder/payload_decoders/window_update_payload_decoder.h"
+#include "net/third_party/quiche/src/http2/http2_structures.h"
+#include "net/third_party/quiche/src/http2/platform/api/http2_export.h"
+
+namespace http2 {
+namespace test {
+class Http2FrameDecoderPeer;
+}  // namespace test
+
+class HTTP2_EXPORT_PRIVATE Http2FrameDecoder {
+ public:
+  explicit Http2FrameDecoder(Http2FrameDecoderListener* listener);
+  Http2FrameDecoder() : Http2FrameDecoder(nullptr) {}
+
+  Http2FrameDecoder(const Http2FrameDecoder&) = delete;
+  Http2FrameDecoder& operator=(const Http2FrameDecoder&) = delete;
+
+  // The decoder will call the listener's methods as it decodes a frame.
+  void set_listener(Http2FrameDecoderListener* listener);
+  Http2FrameDecoderListener* listener() const;
+
+  // The decoder will reject frame's whose payload
+  // length field exceeds the maximum payload size.
+  void set_maximum_payload_size(size_t v) { maximum_payload_size_ = v; }
+  size_t maximum_payload_size() const { return maximum_payload_size_; }
+
+  // Decodes the input up to the next frame boundary (i.e. at most one frame).
+  //
+  // Returns kDecodeDone if it decodes the final byte of a frame, OR if there
+  // is no input and it is awaiting the start of a new frame (e.g. if this
+  // is the first call to DecodeFrame, or if the previous call returned
+  // kDecodeDone).
+  //
+  // Returns kDecodeInProgress if it decodes all of the decode buffer, but has
+  // not reached the end of the frame.
+  //
+  // Returns kDecodeError if the frame's padding or length wasn't valid (i.e. if
+  // the decoder called either the listener's OnPaddingTooLong or
+  // OnFrameSizeError method).
+  DecodeStatus DecodeFrame(DecodeBuffer* db);
+
+  //////////////////////////////////////////////////////////////////////////////
+  // Methods that support Http2FrameDecoderAdapter.
+
+  // Is the remainder of the frame's payload being discarded?
+  bool IsDiscardingPayload() const { return state_ == State::kDiscardPayload; }
+
+  // Returns the number of bytes of the frame's payload that remain to be
+  // decoded, excluding any trailing padding. This method must only be called
+  // after the frame header has been decoded AND DecodeFrame has returned
+  // kDecodeInProgress.
+  size_t remaining_payload() const;
+
+  // Returns the number of bytes of trailing padding after the payload that
+  // remain to be decoded. This method must only be called if the frame type
+  // allows padding, and after the frame header has been decoded AND
+  // DecodeFrame has returned. Will return 0 if the Pad Length field has not
+  // yet been decoded.
+  uint32_t remaining_padding() const;
+
+ private:
+  enum class State {
+    // Ready to start decoding a new frame's header.
+    kStartDecodingHeader,
+    // Was in state kStartDecodingHeader, but unable to read the entire frame
+    // header, so needs more input to complete decoding the header.
+    kResumeDecodingHeader,
+
+    // Have decoded the frame header, and started decoding the available bytes
+    // of the frame's payload, but need more bytes to finish the job.
+    kResumeDecodingPayload,
+
+    // Decoding of the most recently started frame resulted in an error:
+    // OnPaddingTooLong or OnFrameSizeError was called to indicate that the
+    // decoder detected a problem, or OnFrameHeader returned false, indicating
+    // that the listener detected a problem. Regardless of which, the decoder
+    // will stay in state kDiscardPayload until it has been passed the rest
+    // of the bytes of the frame's payload that it hasn't yet seen, after
+    // which it will be ready to decode another frame.
+    kDiscardPayload,
+  };
+
+  friend class test::Http2FrameDecoderPeer;
+  friend std::ostream& operator<<(std::ostream& out, State v);
+
+  DecodeStatus StartDecodingPayload(DecodeBuffer* db);
+  DecodeStatus ResumeDecodingPayload(DecodeBuffer* db);
+  DecodeStatus DiscardPayload(DecodeBuffer* db);
+
+  const Http2FrameHeader& frame_header() const {
+    return frame_decoder_state_.frame_header();
+  }
+
+  // Clear any of the flags in the frame header that aren't set in valid_flags.
+  void RetainFlags(uint8_t valid_flags);
+
+  // Clear all of the flags in the frame header; for use with frame types that
+  // don't define any flags, such as WINDOW_UPDATE.
+  void ClearFlags();
+
+  // These methods call the StartDecodingPayload() method of the frame type's
+  // payload decoder, after first clearing invalid flags in the header. The
+  // caller must ensure that the decode buffer does not extend beyond the
+  // end of the payload (handled by Http2FrameDecoder::StartDecodingPayload).
+  DecodeStatus StartDecodingAltSvcPayload(DecodeBuffer* db);
+  DecodeStatus StartDecodingContinuationPayload(DecodeBuffer* db);
+  DecodeStatus StartDecodingDataPayload(DecodeBuffer* db);
+  DecodeStatus StartDecodingGoAwayPayload(DecodeBuffer* db);
+  DecodeStatus StartDecodingHeadersPayload(DecodeBuffer* db);
+  DecodeStatus StartDecodingPingPayload(DecodeBuffer* db);
+  DecodeStatus StartDecodingPriorityPayload(DecodeBuffer* db);
+  DecodeStatus StartDecodingPushPromisePayload(DecodeBuffer* db);
+  DecodeStatus StartDecodingRstStreamPayload(DecodeBuffer* db);
+  DecodeStatus StartDecodingSettingsPayload(DecodeBuffer* db);
+  DecodeStatus StartDecodingUnknownPayload(DecodeBuffer* db);
+  DecodeStatus StartDecodingWindowUpdatePayload(DecodeBuffer* db);
+
+  // These methods call the ResumeDecodingPayload() method of the frame type's
+  // payload decoder; they are called only if the preceding call to the
+  // corresponding Start method (above) returned kDecodeInProgress, as did any
+  // subsequent calls to the resume method.
+  // Unlike the Start methods, the decode buffer may extend beyond the
+  // end of the payload, so the method will create a DecodeBufferSubset
+  // before calling the ResumeDecodingPayload method of the frame type's
+  // payload decoder.
+  DecodeStatus ResumeDecodingAltSvcPayload(DecodeBuffer* db);
+  DecodeStatus ResumeDecodingContinuationPayload(DecodeBuffer* db);
+  DecodeStatus ResumeDecodingDataPayload(DecodeBuffer* db);
+  DecodeStatus ResumeDecodingGoAwayPayload(DecodeBuffer* db);
+  DecodeStatus ResumeDecodingHeadersPayload(DecodeBuffer* db);
+  DecodeStatus ResumeDecodingPingPayload(DecodeBuffer* db);
+  DecodeStatus ResumeDecodingPriorityPayload(DecodeBuffer* db);
+  DecodeStatus ResumeDecodingPushPromisePayload(DecodeBuffer* db);
+  DecodeStatus ResumeDecodingRstStreamPayload(DecodeBuffer* db);
+  DecodeStatus ResumeDecodingSettingsPayload(DecodeBuffer* db);
+  DecodeStatus ResumeDecodingUnknownPayload(DecodeBuffer* db);
+  DecodeStatus ResumeDecodingWindowUpdatePayload(DecodeBuffer* db);
+
+  FrameDecoderState frame_decoder_state_;
+
+  // We only need one payload decoder at a time, so they share the same storage.
+  union {
+    AltSvcPayloadDecoder altsvc_payload_decoder_;
+    ContinuationPayloadDecoder continuation_payload_decoder_;
+    DataPayloadDecoder data_payload_decoder_;
+    GoAwayPayloadDecoder goaway_payload_decoder_;
+    HeadersPayloadDecoder headers_payload_decoder_;
+    PingPayloadDecoder ping_payload_decoder_;
+    PriorityPayloadDecoder priority_payload_decoder_;
+    PushPromisePayloadDecoder push_promise_payload_decoder_;
+    RstStreamPayloadDecoder rst_stream_payload_decoder_;
+    SettingsPayloadDecoder settings_payload_decoder_;
+    UnknownPayloadDecoder unknown_payload_decoder_;
+    WindowUpdatePayloadDecoder window_update_payload_decoder_;
+  };
+
+  State state_;
+  size_t maximum_payload_size_;
+
+  // Listener used whenever caller passes nullptr to set_listener.
+  Http2FrameDecoderNoOpListener no_op_listener_;
+};
+
+}  // namespace http2
+
+#endif  // QUICHE_HTTP2_DECODER_HTTP2_FRAME_DECODER_H_