Introduce ERR_NETWORK_CHANGED and allow URLFetcher to automatically retry on that error.

net/url_request/url_fetcher.h

 // Copyright (c) 2012 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 NET_URL_REQUEST_URL_FETCHER_H_
 #define NET_URL_REQUEST_URL_FETCHER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 168 matching lines @@
   // will be called, with the URLFetcher's URL set to the redirect destination,
   // its status set to CANCELED, and its response code set to the relevant 3xx
   // server response code.
   virtual void SetStopOnRedirect(bool stop_on_redirect) = 0;
 
   // If |retry| is false, 5xx responses will be propagated to the observer,
   // if it is true URLFetcher will automatically re-execute the request,
   // after backoff_delay() elapses. URLFetcher has it set to true by default.
   virtual void SetAutomaticallyRetryOn5xx(bool retry) = 0;
 
-  virtual void SetMaxRetries(int max_retries) = 0;
-  virtual int GetMaxRetries() const = 0;
+  virtual void SetMaxRetriesOn5xx(int max_retries) = 0;
+  virtual int GetMaxRetriesOn5xx() const = 0;
 
   // Returns the back-off delay before the request will be retried,
   // when a 5xx response was received.
   virtual base::TimeDelta GetBackoffDelay() const = 0;
 
+  // Retries up to |max_retries| times when requests fail with
+  // ERR_NETWORK_CHANGED. If ERR_NETWORK_CHANGED is received after having
+  // retried |max_retries| times then it is propagated to the observer.
+  // Each retry can be delayed if the network if currently offline, and will be
+  // attempted once the network connection is back.

[szym, 2012/12/12 19:50:46]

Not immediately obvious here is that if |max_retries > 0| and
|NetworkChangeNotifier::IsOffline()| then it won't actually start until the next
change to online.

[Joao da Silva, 2012/12/12 20:17:20]

Clarified that in the comment.

+  virtual void SetAutomaticallyRetryOnNetworkChanges(int max_retries) = 0;
+
   // By default, the response is saved in a string. Call this method to save the
   // response to a file instead. Must be called before Start().
   // |file_task_runner| will be used for all file operations.
   // To save to a temporary file, use SaveResponseToTemporaryFile().
   // The created file is removed when the URLFetcher is deleted unless you
   // take ownership by calling GetResponseAsFilePath().
   virtual void SaveResponseToFileAtPath(
       const FilePath& file_path,
       scoped_refptr<base::TaskRunner> file_task_runner) = 0;
 
@@ skipping 57 matching lines @@
   // true, caller takes responsibility for the file, and it will not
   // be removed once the URLFetcher is destroyed.  User should not take
   // ownership more than once, or call this method after taking ownership.
   virtual bool GetResponseAsFilePath(bool take_ownership,
                                      FilePath* out_response_path) const = 0;
 };
 
 }  // namespace net
 
 #endif  // NET_URL_REQUEST_URL_FETCHER_H_