iwyu: Cleanup in the following files:

chrome/browser/autofill/form_field.h

Index: chrome/browser/autofill/form_field.h
diff --git a/chrome/browser/autofill/form_field.h b/chrome/browser/autofill/form_field.h
index 7d663f62b819677685ab10aa76602708f2d2bd6e..70dea644c756f69eea12f7d1bdcd34bb11bc061b 100644
--- a/chrome/browser/autofill/form_field.h
+++ b/chrome/browser/autofill/form_field.h
@@ -8,10 +8,12 @@
 
 #include <vector>
 
+#include "base/basictypes.h"
 #include "base/string16.h"
-#include "base/string_util.h"
 #include "chrome/browser/autofill/autofill_type.h"
-#include "chrome/browser/autofill/form_structure.h"
+
+class AutofillField;
+class FormStructure;
 
 extern const char kEcmlShipToTitle[];
 extern const char kEcmlShipToFirstName[];
@@ -61,8 +63,6 @@ enum FormFieldType {
   kOtherFieldType
 };
 
-class AutofillField;
-
 // Represents a logical form field in a web form.  Classes that implement this
 // interface can identify themselves as a particular type of form field, e.g.
 // name, phone number, or address field.