[Payment Request] Invalidates the update Payment Summary item timer on stop

ios/chrome/browser/ui/payments/payment_request_coordinator.mm

Index: ios/chrome/browser/ui/payments/payment_request_coordinator.mm
diff --git a/ios/chrome/browser/ui/payments/payment_request_coordinator.mm b/ios/chrome/browser/ui/payments/payment_request_coordinator.mm
index 23cc7c817e35aa58ab639fae050bc550ebe694ab..2fe6ef344e32ec9ab119c9dd6e9a271fb3cd8e7a 100644
--- a/ios/chrome/browser/ui/payments/payment_request_coordinator.mm
+++ b/ios/chrome/browser/ui/payments/payment_request_coordinator.mm
@@ -88,6 +88,8 @@ const NSTimeInterval kUpdatePaymentSummaryItemIntervalSeconds = 10.0;
 }
 
 - (void)stop {
+  [_updatePaymentSummaryItemTimer invalidate];
+
   [[_navigationController presentingViewController]
       dismissViewControllerAnimated:YES
                          completion:nil];