Clean up a few more unused globals.

chrome/browser/web_resource/promo_resource_service.cc

Index: chrome/browser/web_resource/promo_resource_service.cc
diff --git a/chrome/browser/web_resource/promo_resource_service.cc b/chrome/browser/web_resource/promo_resource_service.cc
index f4b35fe903cbe470636aeb00143b0cf5fb123647..596356811d8e05b5ba72ec0b7f5c74dcd8088ed4 100644
--- a/chrome/browser/web_resource/promo_resource_service.cc
+++ b/chrome/browser/web_resource/promo_resource_service.cc
@@ -30,10 +30,6 @@ const int kStartResourceFetchDelay = 5000;
 const int kCacheUpdateDelay = 6 * 60 * 60 * 1000;
 const int kTestCacheUpdateDelay = 3 * 60 * 1000;
 
-// The version of the service (used to expire the cache when upgrading Chrome
-// to versions with different types of promos).
-const int kPromoServiceVersion = 7;
-
 // The promotion type used for Unpack() and ScheduleNotificationOnInit().
 const NotificationPromo::PromoType kValidPromoTypes[] = {
 #if defined(OS_ANDROID) || defined(OS_IOS)