Allow asynchronous deferral in NavigationSimulator

content/browser/frame_host/navigation_handle_impl.h

 // Copyright 2015 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.
 
 #ifndef CONTENT_BROWSER_FRAME_HOST_NAVIGATION_HANDLE_IMPL_H_
 #define CONTENT_BROWSER_FRAME_HOST_NAVIGATION_HANDLE_IMPL_H_
 
 #include "content/public/browser/navigation_handle.h"
 
 #include <stddef.h>
@@ skipping 328 matching lines @@
   NavigationType navigation_type() {
     DCHECK_GE(state_, DID_COMMIT);
     return navigation_type_;
   }
 
   void set_response_headers_for_testing(
       scoped_refptr<net::HttpResponseHeaders> response_headers) {
     response_headers_ = response_headers;
   }
 
+  void set_complete_callback_for_testing(
+      const ThrottleChecksFinishedCallback& callback) {
+    complete_callback_for_testing_ = callback;
+  }
+
  private:
   friend class NavigationHandleImplTest;
 
   NavigationHandleImpl(const GURL& url,
                        const std::vector<GURL>& redirect_chain,
                        FrameTreeNode* frame_tree_node,
                        bool is_renderer_initiated,
                        bool is_same_page,
                        const base::TimeTicks& navigation_start,
                        int pending_nav_entry_id,
@@ skipping 81 matching lines @@
 
   // The unique id of the corresponding NavigationEntry.
   int pending_nav_entry_id_;
 
   // The fetch request context type.
   RequestContextType request_context_type_;
 
   // The mixed content context type for potential mixed content checks.
   blink::WebMixedContentContextType mixed_content_context_type_;
 
+  // This callback will be run when all throttle checks have been performed. Be
+  // careful about relying on it as it may be going away.
+  ThrottleChecksFinishedCallback complete_callback_;
+
   // This callback will be run when all throttle checks have been performed.

[clamy, 2017/03/09 13:18:13]

Also mention that this is only used in unit tests, and add a TODO(clamy):
Revisit the unit test architecture when PlzNavigate ships.

-  ThrottleChecksFinishedCallback complete_callback_;
+  ThrottleChecksFinishedCallback complete_callback_for_testing_;
 
   // PlzNavigate
   // Manages the lifetime of a pre-created ServiceWorkerProviderHost until a
   // corresponding ServiceWorkerNetworkProvider is created in the renderer.
   std::unique_ptr<ServiceWorkerNavigationHandle> service_worker_handle_;
 
   // PlzNavigate
   // Manages the lifetime of a pre-created AppCacheHost until a browser side
   // navigation is ready to be committed, i.e we have a renderer process ready
   // to service the navigation request.
@@ skipping 42 matching lines @@
   NavigationType navigation_type_;
 
   base::WeakPtrFactory<NavigationHandleImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NavigationHandleImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_NAVIGATION_HANDLE_IMPL_H_