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

net/url_request/test_url_fetcher_factory.h

Index: net/url_request/test_url_fetcher_factory.h
diff --git a/net/url_request/test_url_fetcher_factory.h b/net/url_request/test_url_fetcher_factory.h
index b1e9e78269001e4673b9661c89c18c00f6e0c621..00911c046e449cffdffa5967428ec111212b03ee 100644
--- a/net/url_request/test_url_fetcher_factory.h
+++ b/net/url_request/test_url_fetcher_factory.h
@@ -109,6 +109,7 @@ class TestURLFetcher : public URLFetcher {
   virtual void SetMaxRetries(int max_retries) OVERRIDE;
   virtual int GetMaxRetries() const OVERRIDE;
   virtual base::TimeDelta GetBackoffDelay() const OVERRIDE;
+  virtual void SetAutomaticallyRetryOnNetworkChanges(int max_retries) OVERRIDE;
   virtual void SaveResponseToFileAtPath(
       const FilePath& file_path,
       scoped_refptr<base::TaskRunner> file_task_runner) OVERRIDE;