Removes usage of signin APIs that return scoped_nsobjects.

ios/chrome/browser/ui/authentication/chrome_signin_view_controller.mm

 // 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.
 
 #include "ios/chrome/browser/ui/authentication/chrome_signin_view_controller.h"
 
 #include <stdint.h>
 #include <cmath>
 #include <memory>
 
@@ skipping 340 matching lines @@
               postSignInAction:POST_SIGNIN_ACTION_NONE
       presentingViewController:self]);
   base::WeakNSObject<ChromeSigninViewController> weakSelf(self);
   [_authenticationFlow startSignInWithCompletion:^(BOOL success) {
     [weakSelf onAccountSigninCompletion:success];
   }];
 }
 
 - (void)openAuthenticationDialogAddIdentity {
   DCHECK(!_interactionManager);
-  _interactionManager =
+  _interactionManager.reset(
       ios::GetChromeBrowserProvider()
           ->GetChromeIdentityService()
-          ->NewChromeIdentityInteractionManager(_browserState, self);
+          ->CreateChromeIdentityInteractionManager(_browserState, self));
   base::WeakNSObject<ChromeSigninViewController> weakSelf(self);
   SigninCompletionCallback completion =
       ^(ChromeIdentity* identity, NSError* error) {
         base::scoped_nsobject<ChromeSigninViewController> strongSelf(
             [weakSelf retain]);
         if (!strongSelf || !strongSelf.get()->_interactionManager)
           return;
         // The ChromeIdentityInteractionManager is not used anymore at this
         // point.
         strongSelf.get()->_interactionManager.reset();
@@ skipping 567 matching lines @@
   }
   _hasConfirmationScreenReachedBottom = YES;
   [self setPrimaryButtonStyling:_primaryButton];
   [_primaryButton setTitle:[self acceptSigninButtonTitle]
                   forState:UIControlStateNormal];
   [_primaryButton setImage:nil forState:UIControlStateNormal];
   [self.view setNeedsLayout];
 }
 
 @end