Implement off-the-wire validation scheme for enum types.

chrome/common/content_settings.h

 // Copyright (c) 2011 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.
 
 #ifndef CHROME_COMMON_CONTENT_SETTINGS_H_
 #define CHROME_COMMON_CONTENT_SETTINGS_H_
 
 #include <string>
 #include <vector>
 
+#include "base/enum_validation.h"
 #include "chrome/common/content_settings_pattern.h"
 #include "chrome/common/content_settings_types.h"
 
 // Different settings that can be assigned for a particular content type.  We
 // give the user the ability to set these on a global and per-origin basis.
 enum ContentSetting {
   CONTENT_SETTING_DEFAULT = 0,
   CONTENT_SETTING_ALLOW,
   CONTENT_SETTING_BLOCK,
   CONTENT_SETTING_ASK,
   CONTENT_SETTING_SESSION_ONLY,
   CONTENT_SETTING_NUM_SETTINGS
 };
+template <> inline bool IsIntValidForEnum<ContentSetting>(int x) {

[darin (slow to review), 2013/05/31 07:11:37]

I don't have a solution to offer, but this feels kind of heavyweight and error
prone.  This code could get out of sync with the enumeration above.  The
developer is essentially indicating the same information twice (i.e., that the
enumeration begins with CONTENT_SETTINGS_DEFAULT and ends with
CONTENT_SETTINGS_NUM_SETTINGS).  Hmm...

+  return x >= CONTENT_SETTING_DEFAULT && x < CONTENT_SETTING_NUM_SETTINGS;
+}
 
 // Range-checked conversion of an int to a ContentSetting, for use when reading
 // prefs off disk.
 ContentSetting IntToContentSetting(int content_setting);
 
 struct ContentSettingPatternSource {
   ContentSettingPatternSource(const ContentSettingsPattern& primary_pattern,
                               const ContentSettingsPattern& secondary_patttern,
                               ContentSetting setting,
                               const std::string& source,
@@ skipping 34 matching lines @@
 // contains the patterns of the appling rule.
 struct SettingInfo {
   SettingSource source;
   ContentSettingsPattern primary_pattern;
   ContentSettingsPattern secondary_pattern;
 };
 
 }  // namespace content_settings
 
 #endif  // CHROME_COMMON_CONTENT_SETTINGS_H_