Fix recursion bug in blocking a fetch and add a test

headless/public/util/managed_dispatch_url_request_job.h

 // Copyright 2016 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 HEADLESS_PUBLIC_UTIL_MANAGED_DISPATCH_URL_REQUEST_JOB_H_
 #define HEADLESS_PUBLIC_UTIL_MANAGED_DISPATCH_URL_REQUEST_JOB_H_
 
 #include "base/macros.h"
 #include "net/base/net_errors.h"
 #include "net/url_request/url_request.h"
 #include "net/url_request/url_request_job.h"
 
 namespace headless {
 class URLRequestDispatcher;
 
 // A ManagedDispatchURLRequestJob exists to allow a URLRequestDispatcher control
 // the order in which a set of fetches complete. Typically this is done to make
 // fetching deterministic. NOTE URLRequestDispatcher sub classes use
 // OnHeadersComplete and OnStartError to drive the URLRequestJob.
 class ManagedDispatchURLRequestJob : public net::URLRequestJob {
  public:
   ManagedDispatchURLRequestJob(net::URLRequest* request,
                                net::NetworkDelegate* network_delegate,
                                URLRequestDispatcher* url_request_dispatcher);
 
   ~ManagedDispatchURLRequestJob() override;
 
   // Tells the net::URLRequestJob that the data has been fetched and is ready to
   // be consumed.
+  // Virtual for FakeManagedDispatchURLRequestJob.
   virtual void OnHeadersComplete();
 
   // Tells the net::URLRequestJob that the fetch failed.
+  // Virtual for FakeManagedDispatchURLRequestJob.
   virtual void OnStartError(net::Error error);
 
  protected:
   // net::URLRequestJob implementation:
   void Kill() override;
 
   // Tell the dispatcher the request failed.
   virtual void DispatchStartError(net::Error error);
 
   // Tell the dispatcher the data is ready for the net stack to consume.
   virtual void DispatchHeadersComplete();
 
   URLRequestDispatcher* url_request_dispatcher_;  // Not owned.
 
  private:
   // Derived classes should not use NotifyHeadersComplete or NotifyStartError
   // directly. Instead they should use DispatchHeadersComplete or
   // DispatchStartError.
   using URLRequestJob::NotifyHeadersComplete;
   using URLRequestJob::NotifyStartError;
 
   DISALLOW_COPY_AND_ASSIGN(ManagedDispatchURLRequestJob);
 };
 
 }  // namespace headless
 
 #endif  // HEADLESS_PUBLIC_UTIL_MANAGED_DISPATCH_URL_REQUEST_JOB_H_