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diff --git a/remoting/protocol/messages_decoder.h b/remoting/protocol/messages_decoder.h
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+++ b/remoting/protocol/messages_decoder.h
@@ -0,0 +1,89 @@
+// Copyright (c) 2010 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 REMOTING_PROTOCOL_MESSAGES_DECODER_H_
+#define REMOTING_PROTOCOL_MESSAGES_DECODER_H_
+
+#include <deque>
+#include <list>
+
+#include "base/ref_counted.h"
+#include "google/protobuf/message_lite.h"
+#include "net/base/io_buffer.h"
+#include "remoting/base/protocol/chromotocol.pb.h"
+
+namespace remoting {
+
+typedef std::list<ChromotingHostMessage*> HostMessageList;
+typedef std::list<ChromotingClientMessage*> ClientMessageList;
+
+// A protocol decoder is used to decode data transmitted in the chromoting
+// network.
+// TODO(hclam): Defines the interface and implement methods.
+class MessagesDecoder {
+ public:
+  MessagesDecoder();
+  virtual ~MessagesDecoder();
+
+  // Parse data received from network into ClientMessages. Output is written
+  // to |messages|.
+  virtual void ParseClientMessages(scoped_refptr<net::IOBuffer> data,
+                                   int data_size,
+                                   ClientMessageList* messages);
+
+  // Parse data received from network into HostMessages. Output is
+  // written to |messages|.
+  virtual void ParseHostMessages(scoped_refptr<net::IOBuffer> data,
+                                 int data_size,
+                                 HostMessageList* messages);
+
+ private:
+  // DataChunk stores reference to a net::IOBuffer and size of the data
+  // stored in that buffer.
+  struct DataChunk {
+    DataChunk(net::IOBuffer* data, size_t data_size)
+        : data(data),
+          data_size(data_size) {
+    }
+
+    scoped_refptr<net::IOBuffer> data;
+    size_t data_size;
+  };
+
+  // TODO(sergeyu): It might be more efficient to memcopy data to one big buffer
+  // instead of storing chunks in dqueue.
+  typedef std::deque<DataChunk> DataList;
+
+  // A private method used to parse data received from network into protocol
+  // buffers.
+  template <typename T>
+  void ParseMessages(scoped_refptr<net::IOBuffer> data,
+                     int data_size,
+                     std::list<T*>* messages);
+
+  // Parse one message from |data_list_|. Return true if sucessful.
+  template <typename T>
+  bool ParseOneMessage(T** messages);
+
+  // A utility method to read payload size of the protocol buffer from the
+  // data list. Return false if we don't have enough data.
+  bool GetPayloadSize(int* size);
+
+  DataList data_list_;
+  size_t last_read_position_;
+
+  // Count the number of bytes in |data_list_| not read.
+  size_t available_bytes_;
+
+  // Stores the size of the next payload if known.
+  size_t next_payload_;
+
+  // True if the size of the next payload is known. After one payload is read,
+  // this is reset to false.
+  bool next_payload_known_;
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_PROTOCOL_MESSAGES_DECODER_H_