[Autofill] Add Chrome flag that annotates web forms with form and field signatures

components/autofill/content/renderer/form_autofill_util.h

Index: components/autofill/content/renderer/form_autofill_util.h
diff --git a/components/autofill/content/renderer/form_autofill_util.h b/components/autofill/content/renderer/form_autofill_util.h
index d268c7c5a5979a9b8562881d766c61d2da398fb4..ccf291570864475cdb07e9dfdb908a7354779285 100644
--- a/components/autofill/content/renderer/form_autofill_util.h
+++ b/components/autofill/content/renderer/form_autofill_util.h
@@ -127,6 +127,10 @@ bool IsCheckableElement(const blink::WebInputElement* element);
 // autofilled. {Text, Radiobutton, Checkbox}.
 bool IsAutofillableInputElement(const blink::WebInputElement* element);
 
+// Returns true if |element| is one of the element types that can be autofilled.
+// {Text, Radiobutton, Checkbox, Select, TextArea}.
+bool IsAutofillableElement(const blink::WebFormControlElement& element);
+
 // True if this node takes up space in the layout, ie. this node or a descendant
 // has a non-empty bounding bounding client rect.
 //