Cleanup: Remove unused SearchTabHelper::GetOpenUrls

chrome/browser/ui/search/search_tab_helper_delegate.cc

Index: chrome/browser/ui/search/search_tab_helper_delegate.cc
diff --git a/chrome/browser/ui/search/search_tab_helper_delegate.cc b/chrome/browser/ui/search/search_tab_helper_delegate.cc
index 38dec64a6ed72103f654ab95ae5c15f5c802b1c0..7b8b9142bf7974504d9766bd06514a3f9f965a1a 100644
--- a/chrome/browser/ui/search/search_tab_helper_delegate.cc
+++ b/chrome/browser/ui/search/search_tab_helper_delegate.cc
@@ -9,11 +9,7 @@ void SearchTabHelperDelegate::OnWebContentsInstantSupportDisabled(
 }
 
 OmniboxView* SearchTabHelperDelegate::GetOmniboxView() {
-  return NULL;
-}
-
-std::set<std::string> SearchTabHelperDelegate::GetOpenUrls() {
-  return std::set<std::string>();
+  return nullptr;
 }
 
 SearchTabHelperDelegate::~SearchTabHelperDelegate() {