Sets the Pay button's title color to white.

ios/chrome/browser/payments/payment_request_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/payments/payment_request_view_controller.h"
 
 #include "base/mac/foundation_util.h"
 
 #include "base/strings/stringprintf.h"
 #include "base/strings/sys_string_conversions.h"
@@ skipping 83 matching lines @@
   ItemTypeContactInfo,
   ItemTypeAddContactInfo,
   ItemTypeFooterText,
 };
 
 }  // namespace
 
 @interface PaymentRequestViewController ()<
     PaymentRequestViewControllerActions> {
   UIBarButtonItem* _cancelButton;
-  MDCFlatButton* _payButton;
+  MDCButton* _payButton;
 
   // The PaymentRequest object having a copy of web::PaymentRequest as provided
   // by the page invoking the Payment Request API. This is a weak pointer and
   // should outlive this class.
   PaymentRequest* _paymentRequest;
 
   __weak PriceItem* _paymentSummaryItem;
   __weak AutofillProfileItem* _selectedShippingAddressItem;
   __weak CollectionViewTextItem* _selectedShippingOptionItem;
   __weak PaymentMethodItem* _selectedPaymentMethodItem;
@@ skipping 25 matching lines @@
                action:@selector(onCancel)];
     [_cancelButton setTitleTextAttributes:@{
       NSForegroundColorAttributeName : [UIColor lightGrayColor]
     }
                                  forState:UIControlStateDisabled];
     [_cancelButton
         setAccessibilityLabel:l10n_util::GetNSString(IDS_ACCNAME_CANCEL)];
     [self navigationItem].leftBarButtonItem = _cancelButton;
 
     // Set up trailing (pay) button.
-    _payButton = [[MDCFlatButton alloc] init];
+    _payButton = [[MDCButton alloc] init];
     [_payButton setTitle:l10n_util::GetNSString(IDS_PAYMENTS_PAY_BUTTON)
                 forState:UIControlStateNormal];
-    [_payButton setBackgroundColor:[[MDCPalette cr_bluePalette] tint500]
-                          forState:UIControlStateNormal];
+    [_payButton setCustomTitleColor:[UIColor whiteColor]];
     [_payButton setInkColor:[UIColor colorWithWhite:1 alpha:0.2]];
-    [_payButton setBackgroundColor:[UIColor grayColor]
-                          forState:UIControlStateDisabled];
     [_payButton addTarget:nil
                    action:@selector(onConfirm)
          forControlEvents:UIControlEventTouchUpInside];
     [_payButton sizeToFit];
     [_payButton setEnabled:(paymentRequest->selected_credit_card() != nil)];
     [_payButton setAutoresizingMask:UIViewAutoresizingFlexibleTrailingMargin() |
                                     UIViewAutoresizingFlexibleTopMargin |
                                     UIViewAutoresizingFlexibleBottomMargin];
 
     // The navigation bar will set the rightBarButtonItem's height to the full
@@ skipping 450 matching lines @@
 
 - (BOOL)collectionView:(UICollectionView*)collectionView
     shouldHideItemBackgroundAtIndexPath:(NSIndexPath*)indexPath {
   // No background on the footer text item.
   NSInteger sectionIdentifier =
       [self.collectionViewModel sectionIdentifierForSection:indexPath.section];
   return sectionIdentifier == SectionIdentifierFooter ? YES : NO;
 }
 
 @end