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

chrome/common/content_settings.h

Index: chrome/common/content_settings.h
diff --git a/chrome/common/content_settings.h b/chrome/common/content_settings.h
index bf92413bc10e9d07f593279604856d7b00e9bc95..18e88b53a7154d73b686e0ca8110f4c26f9e8ccb 100644
--- a/chrome/common/content_settings.h
+++ b/chrome/common/content_settings.h
@@ -8,6 +8,7 @@
 #include <string>
 #include <vector>
 
+#include "base/enum_validation.h"
 #include "chrome/common/content_settings_pattern.h"
 #include "chrome/common/content_settings_types.h"
 
@@ -21,6 +22,9 @@ enum ContentSetting {
   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.