[Popular Sites] Add Variations parameter to override URL path

components/ntp_tiles/pref_names.cc

Index: components/ntp_tiles/pref_names.cc
diff --git a/components/ntp_tiles/pref_names.cc b/components/ntp_tiles/pref_names.cc
index 1988357f410c25347c915fe7da20737f2f7be5c5..c883998736293555ea94bec0625186060cedc0c3 100644
--- a/components/ntp_tiles/pref_names.cc
+++ b/components/ntp_tiles/pref_names.cc
@@ -15,6 +15,10 @@ const char kNumPersonalTiles[] = "ntp.num_personal_suggestions";
 // overrides for country and version below.
 const char kPopularSitesOverrideURL[] = "popular_sites.override_url";
 
+// If set, this will override the URL path directory for popular sites.
+const char kPopularSitesOverrideDirectory[] =
+    "popular_sites.override_directory";
+
 // If set, this will override the country detection for popular sites.
 const char kPopularSitesOverrideCountry[] = "popular_sites.override_country";