Improve error handling in FtpDirectoryListingResponseDelegate.

content/child/ftp_directory_listing_response_delegate.h

 // Copyright 2014 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.
 //
 // A delegate class of WebURLLoaderImpl that handles text/vnd.chromium.ftp-dir
 // data.
 
 #ifndef CONTENT_CHILD_FTP_DIRECTORY_LISTING_RESPONSE_DELEGATE_H_
 #define CONTENT_CHILD_FTP_DIRECTORY_LISTING_RESPONSE_DELEGATE_H_
 
 #include <string>
 
 #include "base/macros.h"
+#include "base/strings/string_piece.h"
 #include "third_party/WebKit/public/platform/WebURLResponse.h"
 
 namespace blink {
 class WebURLLoader;
 class WebURLLoaderClient;
 }
 
 class GURL;
 
 namespace content {
 
 class FtpDirectoryListingResponseDelegate {
  public:
   FtpDirectoryListingResponseDelegate(blink::WebURLLoaderClient* client,
                                       blink::WebURLLoader* loader,
                                       const blink::WebURLResponse& response);
 
   // The request has been canceled, so stop making calls to the client.
   void Cancel();
 
-  // Passed through from ResourceHandleInternal
+  // Called from WebURLLoaderImpl.
   void OnReceivedData(const char* data, int data_len);
-  void OnCompletedRequest();
+  void OnCompletedRequest(int error_code);
 
  private:
   void Init(const GURL& response_url);
 
-  void SendDataToClient(const std::string& data);
+  void SendDataToClient(base::StringPiece data);
 
   // Pointers to the client and associated loader so we can make callbacks as
   // we parse pieces of data.
   blink::WebURLLoaderClient* client_;
   blink::WebURLLoader* loader_;
 
   // Buffer for data received from the network.
   std::string buffer_;
 
   DISALLOW_COPY_AND_ASSIGN(FtpDirectoryListingResponseDelegate);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_FTP_DIRECTORY_LISTING_RESPONSE_DELEGATE_H_