[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 "ui/views/controls/textfield/textfield.h"
+
+namespace payments {
+
+class ValidatingTextfield : public views::Textfield {
+ public:
+  class Delegate {
+   public:

[please use gerrit instead, 2017/02/08 18:50:55]

Need an empty destructor:

"To make sure all implementations of the interface can be destroyed correctly,
the interface must also declare a virtual destructor (in an exception to the
first rule, this should not be pure). See Stroustrup, The C++ Programming
Language, 3rd edition, section 12.4 for details."

https://google.github.io/styleguide/cppguide.html#Interfaces

[Mathieu, 2017/02/08 21:21:50]

Done.

+    // Only the delegate knows how to validate textfield.
+    virtual bool ValidateTextfield(ValidatingTextfield* textfield) = 0;
+  };

[anthonyvd, 2017/02/08 15:28:28]

DISALLOW_COPY_AND_ASSIGN

[Mathieu, 2017/02/08 21:21:51]

Done.

+
+  explicit ValidatingTextfield(ValidatingTextfield::Delegate* delegate);
+
+  // The first validation will happen on blur.
+  void OnBlur() override;

[anthonyvd, 2017/02/08 15:28:28]

nit: comment about where the override is from.

[Mathieu, 2017/02/08 21:21:50]

Done.

+
+  // 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();
+
+  ValidatingTextfield::Delegate* delegate_;
+  bool was_validated_ = false;
+};

[anthonyvd, 2017/02/08 15:28:28]

DISALLOW_COPY_AND_ASSIGN

[Mathieu, 2017/02/08 21:21:50]

Done.

+
+}  // namespace payments
+
+#endif  // CHROME_BROWSER_UI_VIEWS_PAYMENTS_VALIDATING_TEXTFIELD_H_