[WebPayments] Making all fields and buttons focusable

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

Index: chrome/browser/ui/views/payments/validating_combobox.cc
diff --git a/chrome/browser/ui/views/payments/validating_combobox.cc b/chrome/browser/ui/views/payments/validating_combobox.cc
index 0a451d5a40f655580479ef5c9f52d7adb97c3543..e26224270076d93ad92ac54f42acb0326c472d33 100644
--- a/chrome/browser/ui/views/payments/validating_combobox.cc
+++ b/chrome/browser/ui/views/payments/validating_combobox.cc
@@ -16,6 +16,7 @@ ValidatingCombobox::ValidatingCombobox(
     : Combobox(std::move(model)), delegate_(std::move(delegate)) {
   // No need to remove observer on owned model.
   this->model()->AddObserver(this);
+  SetFocusBehavior(FocusBehavior::ALWAYS);
 }
 
 ValidatingCombobox::~ValidatingCombobox() {}