[Payments] Basic validation in the 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/validating_textfield.h"
 
 namespace payments {
 
 class PaymentRequest;
 class PaymentRequestDialogView;
 
 // Credit card editor screen of the Payment Request flow.
 class CreditCardEditorViewController : public EditorViewController {
  public:
   // Does not take ownership of the arguments, which should outlive this object.
   CreditCardEditorViewController(PaymentRequest* request,
                                  PaymentRequestDialogView* dialog);
   ~CreditCardEditorViewController() override;
 
-  // EditorViewController implementation.
+  // EditorViewController:
   std::vector<EditorField> GetFieldDefinitions() override;
   bool ValidateModelAndSave() override;
+  std::unique_ptr<ValidatingTextfield::Delegate> CreateValidationDelegate(
+      const EditorField& field) override;
 
  private:
+  class ValidationDelegate : public ValidatingTextfield::Delegate {
+   public:
+    explicit ValidationDelegate(const EditorField& field);
+    ~ValidationDelegate() override;
+
+    // ValidatingTextfield::Delegate:
+    bool ValidateTextfield(views::Textfield* textfield) override;
+
+   private:
+    EditorField field_;
+
+    DISALLOW_COPY_AND_ASSIGN(ValidationDelegate);
+  };
+
   DISALLOW_COPY_AND_ASSIGN(CreditCardEditorViewController);
 };
 
 }  // namespace payments
 
 #endif  // CHROME_BROWSER_UI_VIEWS_PAYMENTS_CREDIT_CARD_EDITOR_VIEW_CONTROLLER_H_