Instantiate and destroy v4 update manager with IO thread start/stop.

components/safe_browsing_db/database_manager.h

Index: components/safe_browsing_db/database_manager.h
diff --git a/components/safe_browsing_db/database_manager.h b/components/safe_browsing_db/database_manager.h
index 5fa427ff29e086d420d0277507eeaf69d03a537a..9ad4430c592563246f0d50d8b3e5a17d26c9ddd0 100644
--- a/components/safe_browsing_db/database_manager.h
+++ b/components/safe_browsing_db/database_manager.h
@@ -28,6 +28,7 @@ namespace safe_browsing {
 
 struct V4ProtocolConfig;
 class V4GetHashProtocolManager;
+class V4UpdateProtocolManager;
 
 // Base class to either the locally-managed or a remotely-managed database.
 class SafeBrowsingDatabaseManager
@@ -177,6 +178,7 @@ class SafeBrowsingDatabaseManager
 
   // Created and destroyed via StartonIOThread/StopOnIOThread.
   V4GetHashProtocolManager* v4_get_hash_protocol_manager_;
+  V4UpdateProtocolManager* v4_update_protocol_manager_;
 };  // class SafeBrowsingDatabaseManager
 
 }  // namespace safe_browsing