Add ProtoDecoder for sending messages between Host and Controller when pairing

components/pairing/proto_decoder.h

Index: components/pairing/proto_decoder.h
diff --git a/components/pairing/proto_decoder.h b/components/pairing/proto_decoder.h
new file mode 100644
index 0000000000000000000000000000000000000000..e36eb7fce06132e49f05e5a3da38ec27a35e66f1
--- /dev/null
+++ b/components/pairing/proto_decoder.h
@@ -0,0 +1,91 @@
+// Copyright 2014 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 COMPONENTS_PAIRING_PROTO_DECODER_H_
+#define COMPONENTS_PAIRING_PROTO_DECODER_H_
+
+#include <deque>
+
+#include "base/logging.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "components/pairing/message_buffer.h"
+
+namespace net {
+class IOBuffer;
+}
+
+namespace pairing_api {
+class CompleteSetup;
+class ConfigureHost;
+class Error;
+class HostStatus;
+class PairDevices;
+}  // namespace pairing_api
+
+namespace pairing_chromeos {
+
+// A ProtoDecoder collects data from a series of IOBuffers and decodes Proto
+// buffers from the data.  The decoded messages are then forwarded to an
+// observer.
+class ProtoDecoder {
+ public:
+  typedef scoped_refptr<net::IOBuffer> IOBufferRefPtr;
+  class Observer {
+   public:
+    virtual ~Observer() {}
+
+    virtual void OnHostStatusMessage(
+        const pairing_api::HostStatus& message) = 0;
+    virtual void OnConfigureHostMessage(
+        const pairing_api::ConfigureHost& message) = 0;
+    virtual void OnPairDevicesMessage(
+        const pairing_api::PairDevices& message) = 0;
+    virtual void OnCompleteSetupMessage(
+        const pairing_api::CompleteSetup& message) = 0;
+    virtual void OnErrorMessage(
+        const pairing_api::Error& message) = 0;
+
+   protected:
+    Observer() {}
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(Observer);
+  };
+
+  explicit ProtoDecoder(Observer* observer);
+  ~ProtoDecoder();
+
+  // Decodes the data from an io_buffer, and sends out events for any complete
+  // messages.
+  bool DecodeIOBuffer(int size, IOBufferRefPtr io_buffer);
+
+  // Convenience functions for serializing messages into an IOBuffer.
+  static IOBufferRefPtr SendHostStatus(const pairing_api::HostStatus& message,
+                                       int* size);
+  static IOBufferRefPtr SendConfigureHost(
+      const pairing_api::ConfigureHost& message, int* size);
+  static IOBufferRefPtr SendPairDevices(const pairing_api::PairDevices& message,
+                                        int* size);
+  static IOBufferRefPtr SendCompleteSetup(
+      const pairing_api::CompleteSetup& message, int* size);
+  static IOBufferRefPtr SendError(const pairing_api::Error& message, int* size);
+
+ private:
+  static IOBufferRefPtr SendMessage(uint8_t message_type,
+                                    const std::string& message,
+                                    int* size);
+
+  Observer* observer_;
+  MessageBuffer message_buffer_;
+  int next_message_type_;
+  int next_message_size_;
+
+  DISALLOW_COPY_AND_ASSIGN(ProtoDecoder);
+};
+
+}  // namespace pairing_chromeos
+
+#endif  // COMPONENTS_PAIRING_PROTO_DECODER_H_