[Web Payments] Implement the credit card selection UI functionality.

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 {
 
+class PaymentRequest;
+
 // 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
+// expiration 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();
+    // Creates an item that will be owned by |list| with the initial state set
+    // to |selected|.
+    Item(PaymentRequest* request, PaymentRequestItemList* list, bool selected);
     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();
 
+    bool selected() const { return selected_; }
+    // Changes the selected state of this item to |selected| and calls
+    // SelectedStateChanged.
+    void SetSelected(bool selected);
+
+    // Returns a pointer to the PaymentRequestItemList that owns this object.
+    PaymentRequestItemList* list() { return list_; }
+
+    // Returns a pointer to the PaymentRequest object associated with this
+    // instance of the UI.
+    PaymentRequest* request() { return request_; }
+
    protected:
     // Creates and returns the view associated with this list item.
     virtual std::unique_ptr<views::View> CreateItemView() = 0;
 
+    // Called when the selected state of this item changes. Subclasses may
+    // assume that they are the only selected item in |list| when this is
+    // called. This could be called before CreateItemView so subclasses should
+    // be aware that their views might not exist yet.
+    virtual void SelectedStateChanged() = 0;
+
    private:
     std::unique_ptr<views::View> item_view_;
+    PaymentRequest* request_;
+    PaymentRequestItemList* list_;
+    bool selected_;
 
     DISALLOW_COPY_AND_ASSIGN(Item);
   };
 
   PaymentRequestItemList();
   ~PaymentRequestItemList();
 
-  // Adds an item to this list.
+  // Adds an item to this list. |item->list()| should return this object.
   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();
 
+  // Deselects the currently selected item and selects |item| instead.
+  void SelectItem(Item* item);
+
  private:
+  // Unselects the currently selected item. This is private so that the list can
+  // use it when selecting a new item while avoiding consumers of this class
+  // putting the list in a state where no item is selected.
+  void UnselectSelectedItem();
+
   std::vector<std::unique_ptr<Item>> items_;
+  Item* selected_item_;
 
   DISALLOW_COPY_AND_ASSIGN(PaymentRequestItemList);
 };
 
 }  // namespace payments
 
 #endif  // CHROME_BROWSER_UI_VIEWS_PAYMENTS_PAYMENT_REQUEST_ITEM_LIST_H_