[Autofill] A bit of cleanup in autofill_agent.cc

components/autofill/content/renderer/autofill_agent.cc

Index: components/autofill/content/renderer/autofill_agent.cc
diff --git a/components/autofill/content/renderer/autofill_agent.cc b/components/autofill/content/renderer/autofill_agent.cc
index 85f4fad689dba9c397ecd85020a124a18a65f86d..9e48f16f9c57ff717b2c4759bb49e03134678e22 100644
--- a/components/autofill/content/renderer/autofill_agent.cc
+++ b/components/autofill/content/renderer/autofill_agent.cc
@@ -609,10 +609,7 @@ void AutofillAgent::FillAutofillFormData(const WebNode& node,
 void AutofillAgent::SetNodeText(const base::string16& value,
                                 blink::WebInputElement* node) {
   did_set_node_text_ = true;
-  base::string16 substring = value;
-  substring = substring.substr(0, node->maxLength());
-
-  node->setEditingValue(substring);
+  node->setEditingValue(value.substr(0, node->maxLength()));
 }
 
 void AutofillAgent::HideAutofillUI() {