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..73a70594498afda5c0cd1d7417a067b6966228a3
--- /dev/null
+++ b/components/pairing/proto_decoder.h
@@ -0,0 +1,84 @@
+// 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"
+
+namespace net {
+class IOBuffer;
+}
+
+namespace pairing_api {
+class CompleteSetup;
+class ConfigureHost;
+class Error;
+class HostStatus;
+class PairDevices;
+}  // namespace pairing_api
+
+namespace pairing_chromeos {
+
+class MessageBuffer;
+
+// 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:
+  class Observer {
+   public:
+    virtual void OnHostStatusMessage(

[achuithb, 2014/08/11 22:04:31]

Please add a public virtual dtor with an empty body, protected ctor with an
empty body, and private DISALLOW_COPY_AND_ASSIGN.

[Zachary Kuznia, 2014/08/11 23:40:29]

Done.

+        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;
+  };
+
+  explicit ProtoDecoder(Observer* observer);
+  ~ProtoDecoder();
+
+  // Decode the data from an io_buffer, and send out events for any complete

[achuithb, 2014/08/11 22:04:31]

Decodes ..., and sends

[Zachary Kuznia, 2014/08/11 23:40:29]

Done.

+  // messages.
+  bool DecodeIOBuffer(int size, scoped_refptr<net::IOBuffer> io_buffer);

[achuithb, 2014/08/11 22:04:31]

consider using a typedef for scoped_refptr<net::IOBuffer> - this would make this
interface easier to read.

[Zachary Kuznia, 2014/08/11 23:40:29]

Done.

+
+  // Convenience functions for serializing messages into an IOBuffer.
+  static scoped_refptr<net::IOBuffer> SendHostStatus(
+      const pairing_api::HostStatus& message, int* size);
+  static scoped_refptr<net::IOBuffer> SendConfigureHost(
+      const pairing_api::ConfigureHost& message, int* size);
+  static scoped_refptr<net::IOBuffer> SendPairDevices(
+      const pairing_api::PairDevices& message, int* size);
+  static scoped_refptr<net::IOBuffer> SendCompleteSetup(
+      const pairing_api::CompleteSetup& message, int* size);
+  static scoped_refptr<net::IOBuffer> SendError(
+      const pairing_api::Error& message, int* size);
+
+ private:
+  static scoped_refptr<net::IOBuffer> SendMessage(uint8_t message_type,
+                                                  const std::string& message,
+                                                  int* size);
+
+  Observer* observer_;
+  scoped_ptr<MessageBuffer> message_buffer_;

[achuithb, 2014/08/11 22:04:31]

Why not just have a MessageBuffer member:
MessageBuffer message_buffer_;

[Zachary Kuznia, 2014/08/11 23:40:29]

Done.

+  int next_message_type_;
+  int next_message_size_;
+
+  DISALLOW_COPY_AND_ASSIGN(ProtoDecoder);
+};
+
+}  // namespace pairing_chromeos
+
+#endif  // COMPONENTS_PAIRING_PROTO_DECODER_H_