[Payment Request] Refactors the remaining selector view controllers

ios/chrome/browser/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/payments/payment_request_selector_view_controller.h"
 
 #include "base/mac/foundation_util.h"
 #include "components/strings/grit/components_strings.h"
 #import "ios/chrome/browser/payments/cells/payments_text_item.h"
 #import "ios/chrome/browser/payments/payment_request_selector_view_controller_actions.h"
@@ skipping 133 matching lines @@
       if ([cell isKindOfClass:[PaymentsTextCell class]]) {
         PaymentsTextCell* textCell =
             base::mac::ObjCCastStrict<PaymentsTextCell>(cell);
         textCell.textLabel.textColor =
             self.dataSource.state == PaymentRequestSelectorStateError
                 ? [[MDCPalette cr_redPalette] tint600]
                 : [[MDCPalette greyPalette] tint600];
       }
       break;
     }
+    case ItemTypeSelectableItem: {
+      if ([cell isKindOfClass:[PaymentsTextCell class]]) {
+        PaymentsTextCell* textCell =
+            base::mac::ObjCCastStrict<PaymentsTextCell>(cell);
+        textCell.detailTextLabel.textColor = [[MDCPalette greyPalette] tint500];
+      }
+      break;
+    }
     default:
       break;
   }
 
   return cell;
 }
 
 #pragma mark UICollectionViewDelegate
 
 - (void)collectionView:(UICollectionView*)collectionView
@@ skipping 23 matching lines @@
 
       // 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: {
-      [self.delegate paymentRequestSelectorViewControllerDidSelectAddItem:self];
+      if ([self.delegate
+              respondsToSelector:@selector
+              (paymentRequestSelectorViewControllerDidSelectAddItem:)]) {
+        [self.delegate
+            paymentRequestSelectorViewControllerDidSelectAddItem:self];
+      }
       break;
     }
     default:
       break;
   }
 }
 
 #pragma mark MDCCollectionViewStylingDelegate
 
 - (CGFloat)collectionView:(UICollectionView*)collectionView
@@ skipping 15 matching lines @@
     hidesInkViewAtIndexPath:(NSIndexPath*)indexPath {
   NSInteger type = [self.collectionViewModel itemTypeForIndexPath:indexPath];
   if (type == ItemTypeHeader) {
     return YES;
   } else {
     return NO;
   }
 }
 
 @end