Allow CollectionViewModel/Controller queries without SectionIdentifier

ios/chrome/browser/ui/payments/payment_request_selector_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.
 
 #import "ios/chrome/browser/ui/payments/payment_request_selector_view_controller.h"
 
 #include "base/mac/foundation_util.h"
 #include "components/strings/grit/components_strings.h"
 #import "ios/chrome/browser/ui/autofill/cells/status_item.h"
 #import "ios/chrome/browser/ui/collection_view/cells/MDCCollectionViewCell+Chrome.h"
@@ skipping 170 matching lines @@
   CollectionViewItem* item = [model itemAtIndexPath:indexPath];
   switch (item.type) {
     case ItemTypeSelectableItem: {
       // Update the currently selected cell, if any.
       if (self.dataSource.selectedItemIndex != NSUIntegerMax) {
         CollectionViewItem<PaymentsHasAccessoryType>* oldSelectedItem =
             reinterpret_cast<CollectionViewItem<PaymentsHasAccessoryType>*>(
                 [self.dataSource
                     selectableItemAtIndex:self.dataSource.selectedItemIndex]);
         oldSelectedItem.accessoryType = MDCCollectionViewCellAccessoryNone;
-        [self reconfigureCellsForItems:@[ oldSelectedItem ]
-               inSectionWithIdentifier:SectionIdentifierItems];
+        [self reconfigureCellsForItems:@[ oldSelectedItem ]];
       }
 
       // Update the newly selected cell.
       CollectionViewItem<PaymentsHasAccessoryType>* newSelectedItem =
           reinterpret_cast<CollectionViewItem<PaymentsHasAccessoryType>*>(item);
       newSelectedItem.accessoryType = MDCCollectionViewCellAccessoryCheckmark;
-      [self reconfigureCellsForItems:@[ newSelectedItem ]
-             inSectionWithIdentifier:SectionIdentifierItems];
+      [self reconfigureCellsForItems:@[ newSelectedItem ]];
 
       // Notify the delegate of the selection.
       NSUInteger index =
           [self.collectionViewModel indexInItemTypeForIndexPath:indexPath];
       DCHECK(index < [[self.dataSource selectableItems] count]);
       [self.delegate paymentRequestSelectorViewController:self
                                      didSelectItemAtIndex:index];
       break;
     }
     case ItemTypeAddItem: {
@@ skipping 31 matching lines @@
     hidesInkViewAtIndexPath:(NSIndexPath*)indexPath {
   NSInteger type = [self.collectionViewModel itemTypeForIndexPath:indexPath];
   if (type == ItemTypeHeader) {
     return YES;
   } else {
     return NO;
   }
 }
 
 @end