Adding new shipping address editor view to payment flow.

components/autofill/core/browser/country_combobox_model.h

Index: components/autofill/core/browser/country_combobox_model.h
diff --git a/components/autofill/core/browser/country_combobox_model.h b/components/autofill/core/browser/country_combobox_model.h
index b3d90c3abf6d45197ec5b6bbe1a5883710b5ab9e..4e36d91ba459e71b941a7957f21e7f774c0bfeb4 100644
--- a/components/autofill/core/browser/country_combobox_model.h
+++ b/components/autofill/core/browser/country_combobox_model.h
@@ -38,6 +38,8 @@ class CountryComboboxModel : public ui::ComboboxModel {
   base::string16 GetItemAt(int index) override;
   bool IsItemSeparatorAt(int index) override;
 
+  // The list of countries always has the default country at the top as well as
+  // within the sorted vector.
   const CountryVector& countries() const { return countries_; }
 
   // Returns the default country code for this model.