PlzNavigate: make content unit tests work with browser side navigation

content/browser/frame_host/navigator.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.h"
 
 #include "base/time/time.h"
 #include "content/public/browser/stream_handle.h"
 
 namespace content {
@@ skipping 10 matching lines @@
 
 base::TimeTicks Navigator::GetCurrentLoadStart() {
   return base::TimeTicks::Now();
 }
 
 void Navigator::CommitNavigation(FrameTreeNode* frame_tree_node,
                                  ResourceResponse* response,
                                  scoped_ptr<StreamHandle> body) {
 }
 
+bool Navigator::IsWaitingForBeforeUnloadACK(FrameTreeNode* frame_tree_node) {
+  return false;
+}
+
 }  // namespace content