Added ConnectionTimeObserver to calculate the times to authenticate and connect.

remoting/protocol/errors.h

 // Copyright (c) 2012 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_ERROR_H_
 #define REMOTING_PROTOCOL_ERROR_H_
 
+#include "base/logging.h"
+
+#define RETURN_STRING_LITERAL(x) \
+case x: \
+return #x;
+
 namespace remoting {
 namespace protocol {
 
 // The UI implementations maintain corresponding definitions of this
 // enumeration in webapp/error.js and
 // android/java/src/org/chromium/chromoting/jni/JniInterface.java.
 // Be sure to update these locations if you make any changes to the ordering.
 enum ErrorCode {
   OK = 0,
   PEER_IS_OFFLINE,
   SESSION_REJECTED,
   INCOMPATIBLE_PROTOCOL,
   AUTHENTICATION_FAILED,
   CHANNEL_CONNECTION_ERROR,
   SIGNALING_ERROR,
   SIGNALING_TIMEOUT,
   HOST_OVERLOAD,
   UNKNOWN_ERROR,
 };
 
+class Error {

[joedow, 2015/07/29 17:07:02]

Adding a helper method to ConnectionToHost felt fine but this seems awkward
(i.e. defining a class just for a static method).  I think this should be a
namespace instead (or just plop the method in the remoting::protocol namespace.

[tonychun, 2015/07/29 18:30:33]

Done.

+ public:
+  static const char* ProtocolErrorToFriendlyString(ErrorCode error) {
+    switch (error) {
+      RETURN_STRING_LITERAL(OK);
+      RETURN_STRING_LITERAL(PEER_IS_OFFLINE);
+      RETURN_STRING_LITERAL(SESSION_REJECTED);
+      RETURN_STRING_LITERAL(INCOMPATIBLE_PROTOCOL);
+      RETURN_STRING_LITERAL(AUTHENTICATION_FAILED);
+      RETURN_STRING_LITERAL(CHANNEL_CONNECTION_ERROR);
+      RETURN_STRING_LITERAL(SIGNALING_ERROR);
+      RETURN_STRING_LITERAL(SIGNALING_TIMEOUT);
+      RETURN_STRING_LITERAL(HOST_OVERLOAD);
+      RETURN_STRING_LITERAL(UNKNOWN_ERROR);
+      default:
+        LOG(ERROR) << "Unknown error: '" << error << "'";
+        return "UNKNOWN ERROR";
+    }
+  }
+};
+
+
 }  // namespace protocol
 }  // namespace remoting
 
 #endif  // REMOTING_PROTOCOL_ERROR_H_