[Payments] Basic validation in the credit card editor.

chrome/browser/ui/views/payments/validating_textfield.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_VALIDATING_TEXTFIELD_H_
+#define CHROME_BROWSER_UI_VIEWS_PAYMENTS_VALIDATING_TEXTFIELD_H_
+
+#include "base/macros.h"
+#include "ui/views/controls/textfield/textfield.h"
+
+namespace payments {
+
+class ValidatingTextfield : public views::Textfield {
+ public:
+  class Delegate {
+   public:
+    Delegate() {}
+    virtual ~Delegate() {}
+
+    // Only the delegate knows how to validate the textfield.
+    virtual bool ValidateTextfield(views::Textfield* textfield) = 0;
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(Delegate);
+  };
+
+  explicit ValidatingTextfield(
+      std::unique_ptr<ValidatingTextfield::Delegate> delegate);
+  ~ValidatingTextfield() override;
+
+  // Textfield:
+  // The first validation will happen on blur.
+  void OnBlur() override;
+
+  // Called when the textfield contents is changed. May do validation.
+  void OnContentsChanged();
+
+ private:
+  // Will call to the Delegate to validate the contents of the textfield.
+  void Validate();
+
+  std::unique_ptr<ValidatingTextfield::Delegate> delegate_;
+  bool was_validated_ = false;
+
+  DISALLOW_COPY_AND_ASSIGN(ValidatingTextfield);
+};
+
+}  // namespace payments
+
+#endif  // CHROME_BROWSER_UI_VIEWS_PAYMENTS_VALIDATING_TEXTFIELD_H_