Add UKM logging of UPI-VPA autocomplete hints.

components/autofill/core/browser/form_structure.cc

Index: components/autofill/core/browser/form_structure.cc
diff --git a/components/autofill/core/browser/form_structure.cc b/components/autofill/core/browser/form_structure.cc
index 496257e4824868507bf4008a79c5e39304b83b2f..fb32f01eb21ab5215ee82447679a7949546208c1 100644
--- a/components/autofill/core/browser/form_structure.cc
+++ b/components/autofill/core/browser/form_structure.cc
@@ -375,6 +375,8 @@ void FormStructure::DetermineHeuristicTypes(ukm::UkmService* ukm_service) {
   if (has_author_specified_upi_vpa_hint_) {
     AutofillMetrics::LogDeveloperEngagementMetric(
         AutofillMetrics::FORM_CONTAINS_UPI_VPA_HINT);
+    AutofillMetrics::LogDeveloperEngagementUkm(
+        ukm_service, source_url(), AutofillMetrics::FORM_CONTAINS_UPI_VPA_HINT);
   }
 
   AutofillMetrics::LogDetermineHeuristicTypesTiming(