Refactor NavigationHandleImpl::RegisterNavigationThrottles.

content/browser/frame_host/navigation_handle_impl.h

Index: content/browser/frame_host/navigation_handle_impl.h
diff --git a/content/browser/frame_host/navigation_handle_impl.h b/content/browser/frame_host/navigation_handle_impl.h
index 05fd51b502b0175f2e538a56558368fb5268b4e6..cb680ebe1250ba1451fe368f862d270006f46490 100644
--- a/content/browser/frame_host/navigation_handle_impl.h
+++ b/content/browser/frame_host/navigation_handle_impl.h
@@ -429,6 +429,9 @@ class CONTENT_EXPORT NavigationHandleImpl : public NavigationHandle {
   // Populates |throttles_| with the throttles for this navigation.
   void RegisterNavigationThrottles();
 
+  // Takes ownership of |throttle| (if any) and appends it to |throttles_|.
+  void AddThrottle(std::unique_ptr<NavigationThrottle> throttle);
+
   // Checks for attempts to navigate to a page that is already referenced more
   // than once in the frame's ancestors.  This is a helper function used by
   // WillStartRequest and WillRedirectRequest to prevent the navigation.