[PasswordManager] Improve detection of ignorable change password forms.

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 9256b35331ccafc6218a82243cb4bae4db296db3..91f53a454a84ff2daea247f5610f7b24201c6c3e 100644
--- a/components/password_manager/core/browser/password_form_manager.h
+++ b/components/password_manager/core/browser/password_form_manager.h
@@ -86,13 +86,16 @@ class PasswordFormManager : public PasswordStoreConsumer {
 
   // Returns true if the observed form has both the current and new password
   // fields, and the username field was not explicitly marked with
-  // autocomplete=username. In these cases it is not clear whether the username
-  // field is the right guess (often such change password forms do not contain
-  // the username at all), and the user should not be bothered with saving a
-  // potentially malformed credential. Once we handle change password forms
-  // correctly, or http://crbug.com/448351 gets implemented, this method should
-  // be replaced accordingly.
-  bool IsIgnorableChangePasswordForm() const;
+  // "autocomplete=username" and the user-typed username and current password
+  // field values do not match the credentials already stored. In these cases it
+  // is not clear whether the username field is the right guess (often such
+  // change password forms do not contain the username at all), and the user
+  // should not be bothered with saving a potentially malformed credential. Once
+  // we handle change password forms correctly, this method should be replaced
+  // accordingly.
+  bool IsIgnorableChangePasswordForm(
+      const base::string16& typed_username,
+      const base::string16& typed_password) const;
 
   // Determines if the user opted to 'never remember' passwords for this form.
   bool IsBlacklisted() const;