Refactoring PasswordAutofillAgent::FillUserNameAndPassword for early return if...

Refactoring PasswordAutofillAgent::FillUserNameAndPassword for early return if password_element is not autocompleteable.

PasswordAutofillAgent::FillUserNameAndPassword function refactor done for early return as we chould check this at start only.

BUG=398436

Review URL: https://codereview.chromium.org/557703002

Cr-Commit-Position: refs/heads/master@{#295653}

components/autofill/content/renderer/password_autofill_agent.cc

@@ -965,6 +965,10 @@ bool PasswordAutofillAgent::FillUserNameAndPassword(
   base::string16 username;
   base::string16 password;
 
+  // Don't fill username if password can't be set.
+  if (!IsElementAutocompletable(*password_element))
+    return false;
+
   // Look for any suitable matches to current field text.
   if (DoUsernamesMatch(fill_data.basic_data.fields[0].value,
                        current_username,
@@ -1011,11 +1015,6 @@ bool PasswordAutofillAgent::FillUserNameAndPassword(
   // TODO(tkent): Check maxlength and pattern for both username and password
   // fields.
 
-  // Don't fill username if password can't be set.
-  if (!IsElementAutocompletable(*password_element)) {
-    return false;
-  }
-
   // Input matches the username, fill in required values.
   if (IsElementAutocompletable(*username_element)) {
     username_element->setValue(username, true);