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.

[engedy, 2017/03/07 15:24:56]

nit: I am not sure I understand this comment.

[Charlie Harrison, 2017/03/07 16:42:43]

This was indicated by clamy in the subframe navigation filtering throttle CL:
"I really don't want to be modifying the semantic of the callback right now. We
will do it in the future though, where either NavigationHandle will be merged in
the NavigationRequest or NavigationRequest methods will be called directly by
NavigationHandle. This will result in the callback disappearing."

This is why we are adding a new for_testing_ callback instead of reusing this
one.

[engedy, 2017/03/09 11:41:34]

Got it. Let's try to clarify in the comment that "going away" means that the
member will be removed as part of a refactoring, not that the value of it might
become NULL eventually during runtime.

[Charlie Harrison, 2017/03/09 14:36:01]

Done.

+  ThrottleChecksFinishedCallback complete_callback_;
+
   // This callback will be run when all throttle checks have been performed.
-  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_