Block navigations in extensions via ShouldTransferNavigation (not via OpenURL).

content/browser/frame_host/navigator_delegate.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/frame_host/navigator_delegate.h"
 
 namespace content {
 
 bool NavigatorDelegate::CanOverscrollContent() const {
   return false;
 }
 
-bool NavigatorDelegate::ShouldTransferNavigation() {
+bool NavigatorDelegate::ShouldTransferNavigation(
+    bool is_main_frame_navigation) {
   return true;
 }
 
 bool NavigatorDelegate::ShouldPreserveAbortedURLs() {
   return false;
 }
 
 ScopedVector<NavigationThrottle>
 NavigatorDelegate::CreateThrottlesForNavigation(
     NavigationHandle* navigation_handle) {
   return ScopedVector<NavigationThrottle>();
 }
 
 }  // namespace content