[NTP] Refresh promo when users upgrade from M12 to M13.

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 5c55bea45b6cdf5aa4b23157bf13f73798e696d5..c35d0af9e733fdd1b639eaeeb7e6ad2d8570d40e 100644
--- a/chrome/browser/web_resource/promo_resource_service.cc
+++ b/chrome/browser/web_resource/promo_resource_service.cc
@@ -38,7 +38,7 @@ static const int kMaxTimeSliceHours = 24 * 7 * 4;
 
 // The version of the service (used to expire the cache when upgrading Chrome
 // to versions with different types of promos).
-static const int kPromoServiceVersion = 1;
+static const int kPromoServiceVersion = 2;
 
 // Properties used by the server.
 static const char kAnswerIdProperty[] = "answer_id";