[Payments] Add error messages to credit card editor.

chrome/browser/ui/views/payments/credit_card_editor_view_controller.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_VIEWS_PAYMENTS_CREDIT_CARD_EDITOR_VIEW_CONTROLLER_H_
 #define CHROME_BROWSER_UI_VIEWS_PAYMENTS_CREDIT_CARD_EDITOR_VIEW_CONTROLLER_H_
 
 #include "base/macros.h"
 #include "chrome/browser/ui/views/payments/editor_view_controller.h"
 #include "chrome/browser/ui/views/payments/validation_delegate.h"
@@ skipping 17 matching lines @@
   std::vector<EditorField> GetFieldDefinitions() override;
   bool ValidateModelAndSave() override;
   std::unique_ptr<ValidationDelegate> CreateValidationDelegate(
       const EditorField& field) override;
   std::unique_ptr<ui::ComboboxModel> GetComboboxModelForType(
       const autofill::ServerFieldType& type) override;
 
  private:
   class CreditCardValidationDelegate : public ValidationDelegate {
    public:
-    explicit CreditCardValidationDelegate(const EditorField& field);
+    CreditCardValidationDelegate(const EditorField& field,
+                                 EditorViewController* controller);
     ~CreditCardValidationDelegate() override;
 
     // ValidationDelegate:
     bool ValidateTextfield(views::Textfield* textfield) override;
     bool ValidateCombobox(views::Combobox* combobox) override;
 
    private:
     // Validates a specific |value|.
     bool ValidateValue(const base::string16& value);
 
     EditorField field_;
+    // Outlives this class.
+    EditorViewController* controller_;
 
     DISALLOW_COPY_AND_ASSIGN(CreditCardValidationDelegate);
   };
 
   DISALLOW_COPY_AND_ASSIGN(CreditCardEditorViewController);
 };
 
 }  // namespace payments
 
 #endif  // CHROME_BROWSER_UI_VIEWS_PAYMENTS_CREDIT_CARD_EDITOR_VIEW_CONTROLLER_H_