V4Only: In V4Only mode use PVer4 for all SafeBrowsing operations

components/safe_browsing_db/v4_feature_list.h

Index: components/safe_browsing_db/v4_feature_list.h
diff --git a/components/safe_browsing_db/v4_feature_list.h b/components/safe_browsing_db/v4_feature_list.h
index 5bb674836008d50afec1d76948a46ba3b90f4ecb..f549a9556ab9ec9da6148facf014b629acffffd0 100644
--- a/components/safe_browsing_db/v4_feature_list.h
+++ b/components/safe_browsing_db/v4_feature_list.h
@@ -11,13 +11,19 @@ namespace safe_browsing {
 // through Finch.
 namespace V4FeatureList {
 
-// Is the PVer4 database manager enabled?
+// Is the PVer4 database manager enabled? Should be true if either of those
+// below are true.
 bool IsLocalDatabaseManagerEnabled();
 
 // Is the PVer4 database being checked for resource reputation? If this returns
 // true, use PVer4 database for CheckBrowseUrl, otherwise use PVer3.
 bool IsV4HybridEnabled();
 
+// Is only the PVer4 database being checked for resource reputation? If this
+// returns true, use PVer4 database for all SafeBrowsing operations, and don't
+// update the PVer3 database at all.  This is the launch configuration.
+bool IsV4OnlyEnabled();
+
 }  // namespace V4FeatureList
 
 }  // namespace safe_browsing