[Autofill] Pass struct by const-reference.

components/autofill/browser/form_structure.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/autofill/browser/form_structure.h"
 
 #include <utility>
 
 #include "base/basictypes.h"
 #include "base/command_line.h"
@@ skipping 640 matching lines @@
                             UTF16ToUTF8(form_name_) +
                             form_signature_field_names_;
 
   return Hash64Bit(form_string);
 }
 
 bool FormStructure::IsAutocheckoutEnabled() const {
   return !autocheckout_url_prefix_.empty();
 }
 
-bool FormStructure::ShouldSkipField(const FormFieldData field) const {
+bool FormStructure::ShouldSkipField(const FormFieldData& field) const {
   return (field.is_checkable || field.form_control_type == "password") &&
       !IsAutocheckoutEnabled();
 }
 
 size_t FormStructure::RequiredFillableFields() const {
   return IsAutocheckoutEnabled() ? 0 : kRequiredAutofillFields;
 }
 
 bool FormStructure::IsAutofillable(bool require_method_post) const {
   if (autofill_count() < RequiredFillableFields())
@@ skipping 541 matching lines @@
     AutofillType::FieldTypeGroup field_type_group =
         AutofillType((*field)->type()).group();
     if (field_type_group == AutofillType::CREDIT_CARD)
       (*field)->set_section((*field)->section() + "-cc");
     else
       (*field)->set_section((*field)->section() + "-default");
   }
 }
 
 }  // namespace autofill