[Web Payments] Implement item selection in lists.

chrome/browser/ui/views/payments/payment_method_view_controller.cc

Index: chrome/browser/ui/views/payments/payment_method_view_controller.cc
diff --git a/chrome/browser/ui/views/payments/payment_method_view_controller.cc b/chrome/browser/ui/views/payments/payment_method_view_controller.cc
index e940bb7178cf2f3e54660397f78408f9993c07c8..f98e296258eb3a36c840a6ae59e31c8f90afc80d 100644
--- a/chrome/browser/ui/views/payments/payment_method_view_controller.cc
+++ b/chrome/browser/ui/views/payments/payment_method_view_controller.cc
@@ -84,7 +84,8 @@ class PaymentMethodListItem : public payments::PaymentRequestItemList::Item {
   }
 
   void SelectedStateChanged() override {
-    state()->SetSelectedInstrument(instrument_);
+    if (selected())
+      state()->SetSelectedInstrument(instrument_);
   }
 
   bool CanBeSelected() const override {
@@ -108,7 +109,8 @@ PaymentMethodViewController::PaymentMethodViewController(
     PaymentRequestSpec* spec,
     PaymentRequestState* state,
     PaymentRequestDialogView* dialog)
-    : PaymentRequestSheetController(spec, state, dialog) {
+    : PaymentRequestSheetController(spec, state, dialog),
+      payment_method_list_(dialog) {
   const std::vector<std::unique_ptr<PaymentInstrument>>& available_instruments =
       state->available_instruments();