Remove Clone() from CannedBrowsingData*Helper classes

chrome/browser/browsing_data/browsing_data_service_worker_helper.h

Index: chrome/browser/browsing_data/browsing_data_service_worker_helper.h
diff --git a/chrome/browser/browsing_data/browsing_data_service_worker_helper.h b/chrome/browser/browsing_data/browsing_data_service_worker_helper.h
index 47197794e1d69bc350ed90bc0bcac96ace330f50..34ef368df4dafa0ce192458bb3a7e955abfc2d13 100644
--- a/chrome/browser/browsing_data/browsing_data_service_worker_helper.h
+++ b/chrome/browser/browsing_data/browsing_data_service_worker_helper.h
@@ -107,11 +107,6 @@ class CannedBrowsingDataServiceWorkerHelper
   explicit CannedBrowsingDataServiceWorkerHelper(
       content::ServiceWorkerContext* context);
 
-  // Return a copy of the ServiceWorker helper. Only one consumer can use the
-  // StartFetching method at a time, so we need to create a copy of the helper
-  // every time we instantiate a cookies tree model for it.
-  CannedBrowsingDataServiceWorkerHelper* Clone();
-
   // Add a Service Worker to the set of canned Service Workers that is
   // returned by this helper.
   void AddServiceWorker(const GURL& origin, const std::vector<GURL>& scopes);