[Password Manager] Setup experiment to restrict autofilling of sync credential

components/password_manager/core/browser/password_form_manager.cc

Index: components/password_manager/core/browser/password_form_manager.cc
diff --git a/components/password_manager/core/browser/password_form_manager.cc b/components/password_manager/core/browser/password_form_manager.cc
index 1248b11787ab7207efe6975f35a0e3f638cf4103..2fb70adeab1680145ee2e0db2572b529c6c9c9a2 100644
--- a/components/password_manager/core/browser/password_form_manager.cc
+++ b/components/password_manager/core/browser/password_form_manager.cc
@@ -375,11 +375,12 @@ void PasswordFormManager::OnRequestDone(
   // the PasswordForm objects pointed to by the result vector, thus we keep
   // copies to a minimum here.
 
+  bool autofill_result_filtered = false;
   int best_score = 0;
   // These credentials will be in the final result regardless of score.
   std::vector<PasswordForm> credentials_to_keep;
   for (size_t i = 0; i < logins_result.size(); i++) {
-    if (IgnoreResult(*logins_result[i])) {
+    if (IgnoreResult(*logins_result[i], &autofill_result_filtered)) {
       delete logins_result[i];
       continue;
     }
@@ -439,6 +440,9 @@ void PasswordFormManager::OnRequestDone(
   // We're done matching now.
   state_ = POST_MATCHING_PHASE;
 
+  UMA_HISTOGRAM_BOOLEAN("PasswordManager.AutofillResultsFiltered",
+                        autofill_result_filtered);
+
   if (best_score <= 0) {
     return;
   }
@@ -507,7 +511,8 @@ void PasswordFormManager::OnGetPasswordStoreResults(
   OnRequestDone(results);
 }
 
-bool PasswordFormManager::IgnoreResult(const PasswordForm& form) const {
+bool PasswordFormManager::IgnoreResult(const PasswordForm& form,
+                                       bool* autofill_result_filtered) const {
   // Do not autofill on sign-up or change password forms (until we have some
   // working change password functionality).
   if (!observed_form_.new_password_element.empty())
@@ -515,6 +520,11 @@ bool PasswordFormManager::IgnoreResult(const PasswordForm& form) const {
   // Don't match an invalid SSL form with one saved under secure circumstances.
   if (form.ssl_valid && !observed_form_.ssl_valid)
     return true;
+
+  if (client_->ShouldFilterAutofillResult(form)) {
+    *autofill_result_filtered = true;
+    return true;
+  }
   return false;
 }