Add a NavigationThrottle to the public content/ interface

content/browser/frame_host/navigator_delegate.cc

Index: content/browser/frame_host/navigator_delegate.cc
diff --git a/content/browser/frame_host/navigator_delegate.cc b/content/browser/frame_host/navigator_delegate.cc
index 4389c81e2fbcbc881af96f4611db6120394b074b..0ce82f83db8a415b66582a3d53f60d3006b9d63b 100644
--- a/content/browser/frame_host/navigator_delegate.cc
+++ b/content/browser/frame_host/navigator_delegate.cc
@@ -6,6 +6,11 @@
 
 namespace content {
 
+std::vector<NavigationThrottle*> NavigatorDelegate::AddNavigationThrottles(
+    NavigationHandle* navigation_handle) {
+  return std::vector<NavigationThrottle*>();
+}
+
 bool NavigatorDelegate::CanOverscrollContent() const {
   return false;
 }