[Sync] Clean up ModelType code.

components/sync/driver/user_selectable_sync_type.h

Index: components/sync/driver/user_selectable_sync_type.h
diff --git a/components/sync/driver/user_selectable_sync_type.h b/components/sync/driver/user_selectable_sync_type.h
index 95600c91c89b50f830cb38dcebd1e04cd92cd71b..10fb38134a6381298a8589e25ea3ce52e7f49f90 100644
--- a/components/sync/driver/user_selectable_sync_type.h
+++ b/components/sync/driver/user_selectable_sync_type.h
@@ -31,37 +31,12 @@ enum UserSelectableSyncType {
   EXTENSIONS = 6,
   PROXY_TABS = 7,
   APPS = 8,
-  // TODO(petewil): There was talk of removing this from user selectable sync
-  // types.  Should we?
   SYNCED_NOTIFICATIONS = 9,
   WIFI_CREDENTIAL = 10,
-
   READING_LIST = 11,
 
-  // The datatypes below are implicitly synced, and are not exposed via user
-  // selectable checkboxes.
   // TODO(lgcheng) ARC_PACKAGE would be selectable.

[pavely, 2017/02/23 23:23:03]

Maybe add comment here that mapping from user selectable types to full set of
synced types is controlled in SyncPrefs::RegisterPrefGroups?

[skym, 2017/02/24 18:59:07]

Done.

 
-  // AUTOFILL_PROFILE,
-  // NIGORI,
-  // DICTIONARY
-  // SEARCH_ENGINES,
-  // APP_LIST,
-  // APP_SETTINGS,
-  // EXTENSION_SETTINGS,
-  // APP_NOTIFICATIONS,
-  // DEVICE_INFO,
-  // EXPERIMENTS,
-  // PRIORITY_PREFERENCES,
-  // SESSIONS,
-  // HISTORY_DELETE_DIRECTIVES,
-  // FAVICON_IMAGES,
-  // FAVICON_TRACKING,
-  // ARTICLE,
-  // SYNCED_NOTIFICATION_APP_INFO,
-  // ARC_PACKAGE,
-  // PRINTERS
-
   // Number of sync datatypes exposed to the user via checboxes in the UI.
   SELECTABLE_DATATYPE_COUNT = 12,
 };