[Web Payments] Add a mechanism to build item lists in the PR dialog.

chrome/browser/ui/views/payments/payment_request_item_list.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_PAYMENT_REQUEST_ITEM_LIST_H_
+#define CHROME_BROWSER_UI_VIEWS_PAYMENTS_PAYMENT_REQUEST_ITEM_LIST_H_
+
+#include <memory>
+#include <vector>
+
+#include "base/macros.h"
+
+namespace views {
+class View;
+}
+
+namespace payments {
+
+// A control representing a list of selectable items in the PaymentRequest
+// dialog. These lists enforce that only one of their elements be selectable at
+// a time and that "incomplete" items (for example, a credit card with no known
+// expriration date) behave differently when selected. Most of the time, this
+// behavior is to show an editor screen.
+class PaymentRequestItemList {
+ public:
+  // Represents an item in the item list.
+  class Item {
+   public:
+    Item();
+    virtual ~Item();
+
+    // Gets the view associated with this item. It's owned by this object so
+    // that it can listen to any changes to the underlying model and update the
+    // view.
+    views::View* GetItemView();
+
+   protected:
+    // Creates and returns the view associated with this list item.
+    virtual std::unique_ptr<views::View> CreateItemView() = 0;
+
+   private:
+    std::unique_ptr<views::View> item_view_;
+
+    DISALLOW_COPY_AND_ASSIGN(Item);
+  };
+
+  PaymentRequestItemList();
+  ~PaymentRequestItemList();
+
+  // Adds an item to this list.
+  void AddItem(std::unique_ptr<Item> item);
+
+  // Creates and returns the UI representation of this list. It iterates over
+  // the items it contains, creates their associated views, and adds them to the
+  // hierarchy.
+  std::unique_ptr<views::View> CreateListView();
+
+ private:
+  std::vector<std::unique_ptr<Item>> items_;
+
+  DISALLOW_COPY_AND_ASSIGN(PaymentRequestItemList);
+};
+
+}  // namespace payments
+
+#endif  // CHROME_BROWSER_UI_VIEWS_PAYMENTS_PAYMENT_REQUEST_ITEM_LIST_H_