promo_resource_service fixes/cleanup for promos.

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
===================================================================
--- chrome/common/pref_names.cc	(revision 101174)
+++ chrome/common/pref_names.cc	(working copy)
@@ -1277,7 +1277,7 @@
 // True if user has explicitly closed the promo line.
 const char kNTPPromoClosed[] = "ntp.promo_closed";
 
-// Users are randomly divided into 16 groups in order to slowly roll out
+// Users are randomly divided into 100 groups in order to slowly roll out
 // special promos.
 const char kNTPPromoGroup[] = "ntp.promo_group";
 
@@ -1285,6 +1285,9 @@
 // rolled out, in hours.
 const char kNTPPromoGroupTimeSlice[] = "ntp.promo_group_timeslice";
 
+// Number of groups to roll out this promo to.
+const char kNTPPromoGroupMax[] = "ntp.promo_group_max";
+
 // Promo line from server.
 const char kNTPPromoLine[] = "ntp.promo_line";