[Payments] Add support for required fields in editor validation

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

Index: chrome/browser/ui/views/payments/validating_textfield.cc
diff --git a/chrome/browser/ui/views/payments/validating_textfield.cc b/chrome/browser/ui/views/payments/validating_textfield.cc
index ed8dd7d8b8403fbc09e47766f62c474bd29f4f3a..96361cc1d2c84df8b7b6ac44dfbeca4bafd2d44f 100644
--- a/chrome/browser/ui/views/payments/validating_textfield.cc
+++ b/chrome/browser/ui/views/payments/validating_textfield.cc
@@ -17,9 +17,9 @@ ValidatingTextfield::~ValidatingTextfield() {}
 void ValidatingTextfield::OnBlur() {
   Textfield::OnBlur();
 
-  // The first validation of non-empty data should be on a blur. The subsequent
-  // validations will occur when the contents changes.
-  if (!was_validated_ && !text().empty()) {
+  // The first validation should be on a blur. The subsequent validations will
+  // occur when the content changes.
+  if (!was_validated_) {
     was_validated_ = true;
     Validate();
   }