Generalize the usage of referrer chain

chrome/browser/safe_browsing/safe_browsing_service.h

Index: chrome/browser/safe_browsing/safe_browsing_service.h
diff --git a/chrome/browser/safe_browsing/safe_browsing_service.h b/chrome/browser/safe_browsing/safe_browsing_service.h
index 49b5e4e9be6a902d6ec1d664fc4eacaabb57ecaa..1d99f300dd8e17c6827bc5772a47c64fa066d97d 100644
--- a/chrome/browser/safe_browsing/safe_browsing_service.h
+++ b/chrome/browser/safe_browsing/safe_browsing_service.h
@@ -338,9 +338,10 @@ class SafeBrowsingService : public base::RefCountedThreadSafe<
   // both UI and IO thread.
   scoped_refptr<SafeBrowsingDatabaseManager> database_manager_;
 
-  // The navigation observer manager handles download attribution.
+  // The navigation observer manager handles attribution of safe browsing
+  // events.
   scoped_refptr<SafeBrowsingNavigationObserverManager>
-  navigation_observer_manager_;
+      navigation_observer_manager_;
 
   // The password protection service detects and handles password related
   // incidents.