Improve memory usage of safe browsing navigation oberver manager.

chrome/browser/safe_browsing/safe_browsing_navigation_observer_manager.cc

Index: chrome/browser/safe_browsing/safe_browsing_navigation_observer_manager.cc
diff --git a/chrome/browser/safe_browsing/safe_browsing_navigation_observer_manager.cc b/chrome/browser/safe_browsing/safe_browsing_navigation_observer_manager.cc
index 0d14f782777934a9c1bd803b3106d17f4901fd4d..2ebc790a511a410e938f005d73fd73cf0619906c 100644
--- a/chrome/browser/safe_browsing/safe_browsing_navigation_observer_manager.cc
+++ b/chrome/browser/safe_browsing/safe_browsing_navigation_observer_manager.cc
@@ -394,7 +394,7 @@ void SafeBrowsingNavigationObserverManager::AddToReferrerChain(
                                           nav_event->target_tab_id);
   referrer_chain_entry.set_navigation_time_msec(
       nav_event->last_updated.ToJavaTime());
-  referrer_chain->push_back(referrer_chain_entry);
+  referrer_chain->push_back(std::move(referrer_chain_entry));
 }
 
 }  // namespace safe_browsing