Adding the message reading class used for remote_security_key STDIN communication.

remoting/host/security_key/remote_security_key_message_reader.h

+// 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 REMOTING_HOST_SECURITY_KEY_REMOTE_SECURITY_KEY_MESSAGE_READER_H_
+#define REMOTING_HOST_SECURITY_KEY_REMOTE_SECURITY_KEY_MESSAGE_READER_H_
+
+#include "base/callback.h"
+#include "base/files/file.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/thread.h"
+#include "remoting/host/security_key/security_key_message.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}  // namespace base
+
+namespace remoting {
+
+// Used for receiving remote security key messages using a file handle.
+class RemoteSecurityKeyMessageReader {
+ public:
+  explicit RemoteSecurityKeyMessageReader(base::File input_file);
+  ~RemoteSecurityKeyMessageReader();
+
+  // Starts reading messages from the input file provided in the C'Tor.
+  // |message_callback| is called for each received message.
+  // |error_callback| is called in case of an error or the file is closed.
+  // This method is asynchronous, callbacks will be called on the thread this
+  // method is called on.  These callbacks can be called up to the point this
+  // instance is destroyed and may be destroyed as a result of the callback
+  // being invoked.
+  void Start(SecurityKeyMessageCallback message_callback,
+             base::Closure error_callback);
+
+ private:
+  // Reads a message from the remote security key process and passes it to
+  // |message_callback_| on the originating thread. Run on |read_task_runner_|.
+  void ReadMessage();
+
+  // Callback run on |read_task_runner_| when an error occurs or EOF is reached.
+  void NotifyError();
+
+  // Used for callbacks on the appropriate task runner to signal status changes.
+  // These callbacks are invoked on |main_task_runner_|.
+  void InvokeMessageCallback(scoped_ptr<SecurityKeyMessage> message);
+  void InvokeErrorCallback();
+
+  base::File read_stream_;
+
+  // Caller-supplied message and error callbacks.
+  SecurityKeyMessageCallback message_callback_;
+  base::Closure error_callback_;
+
+  // Thread used for blocking IO operations.
+  base::Thread reader_thread_;
+  scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
+  scoped_refptr<base::SingleThreadTaskRunner> read_task_runner_;
+
+  base::WeakPtr<RemoteSecurityKeyMessageReader> reader_;
+  base::WeakPtrFactory<RemoteSecurityKeyMessageReader> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(RemoteSecurityKeyMessageReader);
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_SECURITY_KEY_REMOTE_SECURITY_KEY_MESSAGE_READER_H_