[WebPayments] Implement state transitions in desktop WebPayments dialog.

chrome/browser/payments/ui/payment_dialog_state.h

+// Copyright 2016 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_PAYMENTS_UI_PAYMENT_DIALOG_STATE_H_
+#define CHROME_BROWSER_PAYMENTS_UI_PAYMENT_DIALOG_STATE_H_
+
+#include "base/macros.h"
+
+namespace views {
+class View;
+}
+
+namespace payments {
+
+// Base class for the different WebPayments UI states.
+class PaymentDialogState {
+ public:
+  // Create the view associated with this state if needed and return it.
+  virtual views::View* GetView() = 0;

[please use gerrit instead, 2016/11/22 21:39:33]

Specify who owns the returned view.

[anthonyvd, 2016/11/22 22:11:19]

Done.

+
+  // Marks the state as interactable or not depending on |interactable|. States
+  // should be marked as non-interactable when they are being transitioned out
+  // or have another state being transitioned in on top of them. A non-
+  // interactable state shouldn't trigger events at all. This is to prevent non-
+  // foreground states from being interacted with.
+  void SetInteractable(bool interactable) {
+    interactable_ = interactable;
+  }
+
+  bool interactable() { return interactable_; }
+
+ protected:
+  PaymentDialogState() {}

[please use gerrit instead, 2016/11/22 21:39:32]

Rule of thumb is that a constructor should always be followed by a destructor.

[anthonyvd, 2016/11/22 22:11:19]

Done. Moved to public to satisfy unique_ptr template voodoo.

+
+ private:
+  bool interactable_;
+  DISALLOW_COPY_AND_ASSIGN(PaymentDialogState);
+};
+
+}  // namespace payments
+
+#endif  // CHROME_BROWSER_PAYMENTS_UI_PAYMENT_DIALOG_STATE_H_