Restructure URLRequestSlowDownloadJob to avoid races.

content/browser/net/url_request_slow_download_job.h

 // Copyright (c) 2011 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.
 // This class simulates a slow download.  This used in a UI test to test the
 // download manager.  Requests to |kUnknownSizeUrl| and |kKnownSizeUrl| start
 // downloads that pause after the first N bytes, to be completed by sending a
 // request to |kFinishDownloadUrl|.
 
 #ifndef CONTENT_BROWSER_NET_URL_REQUEST_SLOW_DOWNLOAD_JOB_H_
 #define CONTENT_BROWSER_NET_URL_REQUEST_SLOW_DOWNLOAD_JOB_H_
@@ skipping 35 matching lines @@
   // not yet completed.
   CONTENT_EXPORT static size_t NumberOutstandingRequests();
 
   // Adds the testing URLs to the net::URLRequestFilter.
   CONTENT_EXPORT static void AddUrlHandler();
 
  private:
   explicit URLRequestSlowDownloadJob(net::URLRequest* request);
   virtual ~URLRequestSlowDownloadJob();
 
+  // Enum indicating where we are in the read after a call to
+  // FillBufferHelper.
+  enum ReadStatus {
+    // The buffer was filled with data and may be returned.
+    BUFFER_FILLED,
+
+    // No data was added to the buffer because kFinishDownloadUrl has
+    // not yet been seen and we've already returned the first chunk.
+    REQUEST_BLOCKED,
+
+    // No data was added to the buffer because we've already returned
+    // all the data.
+    REQUEST_COMPLETE
+  };
+  ReadStatus FillBufferHelper(
+      net::IOBuffer* buf,
+      int buf_size,
+      int* bytes_written);
+
   void GetResponseInfoConst(net::HttpResponseInfo* info) const;
 
   // Mark all pending requests to be finished.  We keep track of pending
   // requests in |pending_requests_|.
   static void FinishPendingRequests();
   typedef std::set<URLRequestSlowDownloadJob*> SlowJobsSet;
   static base::LazyInstance<SlowJobsSet,
                             base::LeakyLazyInstanceTraits<SlowJobsSet> >
       pending_requests_;
 
   void StartAsync();
 
   void set_should_finish_download() { should_finish_download_ = true; }
 
-  int first_download_size_remaining_;
+  int bytes_already_sent_;
   bool should_finish_download_;
   scoped_refptr<net::IOBuffer> buffer_;
   int buffer_size_;
 
   base::WeakPtrFactory<URLRequestSlowDownloadJob> weak_factory_;
 };
 
 #endif  // CONTENT_BROWSER_NET_URL_REQUEST_SLOW_DOWNLOAD_JOB_H_