Generalize the usage of referrer chain

chrome/browser/safe_browsing/safe_browsing_navigation_observer.h

Index: chrome/browser/safe_browsing/safe_browsing_navigation_observer.h
diff --git a/chrome/browser/safe_browsing/safe_browsing_navigation_observer.h b/chrome/browser/safe_browsing/safe_browsing_navigation_observer.h
index 8414d418e8358300217c1e23512aa689265628d4..15030a65324a0c3a707fcea0148c183df839f983 100644
--- a/chrome/browser/safe_browsing/safe_browsing_navigation_observer.h
+++ b/chrome/browser/safe_browsing/safe_browsing_navigation_observer.h
@@ -17,8 +17,8 @@ namespace safe_browsing {
 class SafeBrowsingNavigationObserverManager;
 
 // Struct to record the details of a navigation event for any frame.
-// This information will be used to fill |url_chain| field in safe browsing
-// download pings.
+// This information will be used to fill referrer chain info in various Safe
+// Browsing requests and reports.
 struct NavigationEvent {
   NavigationEvent();
   NavigationEvent(NavigationEvent&& nav_event);