AutoFill credit card settings dialog should display obfuscated number in edit field

chrome/browser/autofill/autofill_credit_card_sheet_controller_mac.mm

 // Copyright (c) 2010 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 "chrome/browser/autofill/autofill_credit_card_sheet_controller_mac.h"
 
 #include "app/l10n_util.h"
 #include "base/mac_util.h"
 #include "base/sys_string_conversions.h"
 #import "chrome/browser/autofill/autofill_credit_card_model_mac.h"
 #import "chrome/browser/autofill/autofill_dialog_controller_mac.h"
 #include "chrome/browser/autofill/credit_card.h"
 #include "grit/generated_resources.h"
 
+// Interface exposed for unit testing.
+@implementation AutoFillCreditCardSheetController (ExposedForUnitTests)
+- (NSTextField*)creditCardNumberField {
+  return creditCardNumberField_;
+}
+@end
+
 // Private methods for the |AutoFillCreditCardSheetController| class.
 @interface AutoFillCreditCardSheetController (PrivateMethods)
 - (void)buildBillingAddressContents;
 - (void)buildExpirationMonthContents;
 - (void)buildExpirationYearContents;
 @end
 
 @implementation AutoFillCreditCardSheetController
 
 @synthesize creditCardModel = creditCardModel_;
@@ skipping 131 matching lines @@
         indexOfObject:[creditCardModel_ expirationYear]] == NSNotFound) {
     [creditCardModel_ setExpirationYear:@" "];
   }
 
   // Disable first item in menu.  @" " is a non-item.
   [[expirationYearPopup_ itemAtIndex:0] setEnabled:NO];
 }
 
 @end