Added ConnectionTimeObserver to calculate the times to authenticate and connect.

remoting/test/connection_time_observer.h

+// Copyright 2015 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_TEST_CONNECTION_TIME_OBSERVER_H_
+#define REMOTING_TEST_CONNECTION_TIME_OBSERVER_H_
+
+#include "remoting/test/remote_connection_observer.h"
+
+namespace remoting {
+namespace test {
+
+// Observes and calculates the time between each state change of the chromoting
+// connection process.

[Sergey Ulanov, 2015/07/20 23:04:04]

And it also logs the calculated values. The purpose is not clear without
mentioning it in the comment, because the class doesn't provide any way to get
these latency values. Alternatively the class can just store the number and
provide GetStateTransitionDelay() method to get them.

[tonychun, 2015/07/23 03:31:04]

Done.

+class ConnectionTimeObserver
+    : public RemoteConnectionObserver {
+ public:
+  ConnectionTimeObserver();
+  ~ConnectionTimeObserver() override;
+
+  // RemoteConnectionObserver interface.
+  void ConnectionStateChanged(protocol::ConnectionToHost::State state,
+                              protocol::ErrorCode error_code) override;
+
+ private:
+  // Saves the latest state the ChromotingClient is in.
+  protocol::ConnectionToHost::State current_state_;
+
+  // Used to find the time difference between subsequent calls to
+  // ConnectionStateChanged.
+  base::TimeTicks last_state_change_time_ticks;

[Sergey Ulanov, 2015/07/20 23:04:04]

nit: call it last_state_change_time_ or last_state_change_ticks_ - both are just
as clear and shorter.

[Sergey Ulanov, 2015/07/20 23:04:04]

add _ at the end of the name

[tonychun, 2015/07/23 03:31:04]

Done.

+
+  DISALLOW_COPY_AND_ASSIGN(ConnectionTimeObserver);
+};
+
+}  // namespace test
+}  // namespace remoting
+
+#endif  // REMOTING_TEST_CONNECTION_TIME_OBSERVER_H_