Adding error handling to the connection flow.

remoting/ios/app/client_connection_view_controller.h

 // 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.
 
 #ifndef REMOTING_IOS_APP_CLIENT_CONNECTION_VIEW_CONTROLLER_H_
 #define REMOTING_IOS_APP_CLIENT_CONNECTION_VIEW_CONTROLLER_H_
 
 #import <UIKit/UIKit.h>
 
 @class HostInfo;
 
 // This enumerated the differnt modes this Client Connection View can be in.
 typedef NS_ENUM(NSInteger, ClientConnectionViewState) {
   ClientViewConnecting,
   ClientViewPinPrompt,
   ClientViewConnected,
   ClientViewClosed,
+  ClientViewError,
 };
 
 // This is the view that shows the user feedback while the client connection is
 // being established. If requested the view can also display the pin entry view.
 // State communication for this view is handled by NSNotifications, it listens
 // to kHostSessionStatusChanged events on the default NSNotificationCenter.
 // Internally the notification is tied to [self setState] so view setup will
 // work the same way if state is set directly.
 @interface ClientConnectionViewController : UIViewController
 
 - (instancetype)initWithHostInfo:(HostInfo*)hostInfo;
 
 // Setting state will change the view
 @property(nonatomic, assign) ClientConnectionViewState state;
 
 @end
 
 #endif  // REMOTING_IOS_APP_CLIENT_CONNECTION_VIEW_CONTROLLER_H_