Autofill: Set requirements for number of recognized fields in an autofillable form

components/autofill/core/browser/email_field.cc

 // Copyright 2013 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/core/browser/email_field.h"
 
+#include "base/logging.h"
 #include "base/strings/utf_string_conversions.h"
 #include "components/autofill/core/browser/autofill_regex_constants.h"
 #include "components/autofill/core/browser/autofill_scanner.h"
 
 namespace autofill {
 
 // static
 scoped_ptr<FormField> EmailField::Parse(AutofillScanner* scanner) {
   AutofillField* field;
   if (ParseFieldSpecifics(scanner, base::UTF8ToUTF16(kEmailRe),
                           MATCH_DEFAULT | MATCH_EMAIL, &field)) {
     return make_scoped_ptr(new EmailField(field));
   }
 
   return NULL;
 }
 
 EmailField::EmailField(const AutofillField* field) : field_(field) {
+  DCHECK(field);
 }
 
 bool EmailField::ClassifyField(ServerFieldTypeMap* map) const {
   return AddClassification(field_, EMAIL_ADDRESS, map);
 }
 
+size_t EmailField::FieldCount() const {
+  return 1;
+}
+
 }  // namespace autofill