Adding error handling to the connection flow.

remoting/ios/domain/client_session_details.mm

 // Copyright 2017 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.
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 #import "remoting/ios/domain/client_session_details.h"
 
 #import "remoting/ios/domain/host_info.h"
 
 @implementation ClientSessionDetails
 
 @synthesize hostInfo = _hostInfo;
 @synthesize state = _state;
+@synthesize error = _error;
 
 - (NSString*)description {
   return
       [NSString stringWithFormat:@"ClientSessionDetails: state=%d hostInfo=%@",
                                  (int)_state, _hostInfo];
 }
 
 @end