Add metrics to track Autofill "user happiness"

chrome/browser/autofill/form_structure.cc

Index: chrome/browser/autofill/form_structure.cc
diff --git a/chrome/browser/autofill/form_structure.cc b/chrome/browser/autofill/form_structure.cc
index 67f05fdf467c460ac6500027af5d2bc47ba18342..6bf227d382647d97f840fa2247f3965e661cfe29 100644
--- a/chrome/browser/autofill/form_structure.cc
+++ b/chrome/browser/autofill/form_structure.cc
@@ -635,6 +635,7 @@ void FormStructure::LogQualityMetrics(
   std::string experiment_id = server_experiment_id();
   metric_logger.LogServerExperimentIdForUpload(experiment_id);
 
+  size_t num_detected_field_types = 0;
   for (size_t i = 0; i < field_count(); ++i) {
     const AutofillField* field = this->field(i);
     metric_logger.LogQualityMetric(AutofillMetrics::FIELD_SUBMITTED,
@@ -647,6 +648,8 @@ void FormStructure::LogQualityMetrics(
     if (field_types.count(EMPTY_TYPE) || field_types.count(UNKNOWN_TYPE))
       continue;
 
+    ++num_detected_field_types;
+
     // Collapse field types that Chrome treats as identical, e.g. home and
     // billing address fields.
     FieldTypeSet collapsed_field_types;
@@ -750,16 +753,11 @@ void FormStructure::LogQualityMetrics(
       }
     }
   }
-}
 
-void FormStructure::set_possible_types(size_t index,
-                                       const FieldTypeSet& types) {
-  if (index >= fields_.size()) {
-    NOTREACHED();
-    return;
+  if (num_detected_field_types >= kRequiredFillableFields) {
+    metric_logger.LogUserHappinessMetric(
+        AutofillMetrics::SUBMITTED_FORM_COULD_HAVE_BEEN_AUTOFILLED);
   }
-
-  fields_[index]->set_possible_types(types);
 }
 
 const AutofillField* FormStructure::field(size_t index) const {
@@ -771,6 +769,11 @@ const AutofillField* FormStructure::field(size_t index) const {
   return fields_[index];
 }
 
+AutofillField* FormStructure::field(size_t index) {
+  return const_cast<AutofillField*>(
+      static_cast<const FormStructure*>(this)->field(index));
+}
+
 size_t FormStructure::field_count() const {
   return fields_.size();
 }