Allow CollectionViewModel/Controller queries without SectionIdentifier

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

 // Copyright 2016 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.
 
 #import "ios/chrome/browser/ui/authentication/signed_in_accounts_view_controller.h"
 
 #import "base/mac/foundation_util.h"
 #include "components/signin/core/browser/account_tracker_service.h"
 #include "components/signin/core/browser/profile_oauth2_token_service.h"
 #include "components/signin/ios/browser/oauth2_token_service_observer_bridge.h"
@@ skipping 148 matching lines @@
   return YES;
 }
 
 #pragma mark ChromeIdentityServiceObserver
 
 - (void)onProfileUpdate:(ChromeIdentity*)identity {
   CollectionViewAccountItem* item =
       base::mac::ObjCCastStrict<CollectionViewAccountItem>(
           [_identityMap objectForKey:identity.gaiaID]);
   [self updateAccountItem:item withIdentity:identity];
-  NSIndexPath* indexPath =
-      [self.collectionViewModel indexPathForItem:item
-                         inSectionWithIdentifier:SectionIdentifierAccounts];
+  NSIndexPath* indexPath = [self.collectionViewModel indexPathForItem:item];
   [self.collectionView reloadItemsAtIndexPaths:@[ indexPath ]];
 }
 
 - (void)onChromeIdentityServiceWillBeDestroyed {
   _identityServiceObserver.reset();
 }
 
 @end
 
 @interface SignedInAccountsViewController ()<
@@ skipping 202 matching lines @@
       OAuth2TokenServiceFactory::GetForBrowserState(_browserState);
   if (tokenService->GetAccounts().empty()) {
     [self dismiss];
     return;
   }
   [_accountsCollection loadModel];
   [_accountsCollection.get().collectionView reloadData];
 }
 
 @end