Remove unused ThumbnailDatabase::UpdateIconMapping() and ThumbnailDatabase::CloneIconMappings()

components/history/core/browser/history_backend.cc

Index: components/history/core/browser/history_backend.cc
diff --git a/components/history/core/browser/history_backend.cc b/components/history/core/browser/history_backend.cc
index c257a7652bb8881fead51f17dad9ed6892134235..4abcca45fe04d78d6756c9a34fc96a1f4bcbc865 100644
--- a/components/history/core/browser/history_backend.cc
+++ b/components/history/core/browser/history_backend.cc
@@ -1769,19 +1769,6 @@ void HistoryBackend::SetFaviconsOutOfDateForPage(const GURL& page_url) {
   ScheduleCommit();
 }
 
-void HistoryBackend::CloneFavicons(const GURL& old_page_url,
-                                   const GURL& new_page_url) {
-  if (!thumbnail_db_)
-    return;
-
-  // Prevent cross-domain cloning.
-  if (old_page_url.GetOrigin() != new_page_url.GetOrigin())
-    return;
-
-  thumbnail_db_->CloneIconMappings(old_page_url, new_page_url);
-  ScheduleCommit();
-}
-
 void HistoryBackend::SetImportedFavicons(
     const favicon_base::FaviconUsageDataList& favicon_usage) {
   if (!db_ || !thumbnail_db_)