[CRD iOS] Fix the leaky RemotingClient

remoting/ios/app/remoting_view_controller.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/app/remoting_view_controller.h"
 
@@ skipping 170 matching lines @@
 // updated"...
 - (void)hostListUpdated {
   [_collectionViewController.collectionView reloadData];
 }
 
 #pragma mark - ClientConnectionViewControllerDelegate
 
 - (void)clientConnected {
   HostViewController* hostViewController =
       [[HostViewController alloc] initWithClient:_client];
+  _client = nil;
   [self presentViewController:hostViewController animated:YES completion:nil];
 }
 
 - (NSString*)getConnectingHostName {
   if (_client) {
     return _client.hostInfo.hostName;
   }
   return nil;
 }
 
@@ skipping 86 matching lines @@
   MDCSnackbarMessage* message = [[MDCSnackbarMessage alloc] init];
   if (_isAuthenticated) {
     message.text = [NSString
         stringWithFormat:@"Currently signed in as %@.",
                          _remotingService.authentication.user.userEmail];
     [MDCSnackbarManager showMessage:message];
   }
 }
 
 @end