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

components/password_manager/core/browser/password_form_manager.h

Index: components/password_manager/core/browser/password_form_manager.h
diff --git a/components/password_manager/core/browser/password_form_manager.h b/components/password_manager/core/browser/password_form_manager.h
index 89c6933f4da207fbd7b76e273b917f8513bc265e..d650a43665becfb20b3cd9cf47f2d28945a2e2ab 100644
--- a/components/password_manager/core/browser/password_form_manager.h
+++ b/components/password_manager/core/browser/password_form_manager.h
@@ -218,8 +218,11 @@ class PasswordFormManager : public PasswordStoreConsumer {
                                          kSubmitResultMax;
 
   // Helper for OnGetPasswordStoreResults to determine whether or not
-  // the given result form is worth scoring.
-  bool IgnoreResult(const autofill::PasswordForm& form) const;
+  // the given result form is worth scoring. |autofill_result_filtered| is set
+  // to true iff a result is dropped because the |client_| requested that
+  // it be filtered (e.g. the form matches the user's sync credentials).
+  bool ShouldIgnoreResult(const autofill::PasswordForm& form,
+                          bool* autofill_result_filtered) const;
 
   // Helper for Save in the case that best_matches.size() == 0, meaning
   // we have no prior record of this form/username/password and the user