[Payments] Add support for required fields in editor validation

chrome/browser/ui/views/payments/editor_view_controller.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_EDITOR_VIEW_CONTROLLER_H_
 #define CHROME_BROWSER_UI_VIEWS_PAYMENTS_EDITOR_VIEW_CONTROLLER_H_
 
 #include <memory>
 #include <unordered_map>
 #include <vector>
@@ skipping 16 matching lines @@
 
 class PaymentRequest;
 class PaymentRequestDialogView;
 
 // Field definition for an editor field, used to build the UI.
 struct EditorField {
   enum class LengthHint : int { HINT_LONG, HINT_SHORT };
 
   EditorField(autofill::ServerFieldType type,
               const base::string16& label,
-              LengthHint length_hint)
-      : type(type), label(label), length_hint(length_hint) {}
+              LengthHint length_hint,
+              bool required)
+      : type(type),
+        label(label),
+        length_hint(length_hint),
+        required(required) {}
 
+  // Data type in the field.
   const autofill::ServerFieldType type;
+  // Label to be shown alongside the field.
   const base::string16 label;
+  // Hint about the length of this field's contents.
   LengthHint length_hint;
+  // Whether the field is required.
+  bool required;
 };
 
 // The PaymentRequestSheetController subtype for the editor screens of the
 // Payment Request flow.
 class EditorViewController : public PaymentRequestSheetController,
                              public views::TextfieldController {
  public:
   using TextFieldsMap =
       std::unordered_map<ValidatingTextfield*, const EditorField>;
 
@@ skipping 38 matching lines @@
   // parent view, this only keeps a reference that is good as long as the
   // textfield is visible.
   TextFieldsMap text_fields_;
 
   DISALLOW_COPY_AND_ASSIGN(EditorViewController);
 };
 
 }  // namespace payments
 
 #endif  // CHROME_BROWSER_UI_VIEWS_PAYMENTS_EDITOR_VIEW_CONTROLLER_H_