drive: Return cancel closure from FileSystem::GetFileContent

chrome/browser/chromeos/drive/drive_file_stream_reader.h

 // Copyright 2013 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 CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_FILE_STREAM_READER_H_
 #define CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_FILE_STREAM_READER_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 154 matching lines @@
   // If no data is available yet, returns net::ERR_IO_PENDING immediately,
   // and when the data is available the actual Read operation is done
   // and |callback| will be run with the result.
   // The Read() method must not be called before the Initialize() is completed
   // successfully, or if there is pending read operation.
   // Neither |buffer| nor |callback| must be null.
   int Read(net::IOBuffer* buffer, int buffer_length,
            const net::CompletionCallback& callback);
 
  private:
+  // Used to store the cancel closure returned by FileSystemInterface.
+  void StoreCancelDownloadClosure(const base::Closure& cancel_download_closure);
+
   // Part of Initialize. Called after GetFileContent's initialization
   // is done.
   void InitializeAfterGetFileContentInitialized(
       const net::HttpByteRange& byte_range,
       const InitializeCompletionCallback& callback,
       FileError error,
-      scoped_ptr<ResourceEntry> entry,
       const base::FilePath& local_cache_file_path,
-      const base::Closure& cancel_download_closure);
+      scoped_ptr<ResourceEntry> entry);
 
   // Part of Initialize. Called when the local file open process is done.
   void InitializeAfterLocalFileOpen(
       int64 length,
       const InitializeCompletionCallback& callback,
       scoped_ptr<ResourceEntry> entry,
       scoped_ptr<util::LocalFileReader> file_reader,
       int open_result);
 
   // Called when the data is received from the server.
   void OnGetContent(google_apis::GDataErrorCode error_code,
                     scoped_ptr<std::string> data);
 
   // Called when GetFileContent is completed.
   void OnGetFileContentCompletion(
       const InitializeCompletionCallback& callback,
       FileError error);
 
   const FileSystemGetter file_system_getter_;
   scoped_refptr<base::SequencedTaskRunner> file_task_runner_;
+  base::Closure cancel_download_closure_;
   scoped_ptr<internal::ReaderProxy> reader_proxy_;
 
   // This should remain the last member so it'll be destroyed first and
   // invalidate its weak pointers before other members are destroyed.
   base::WeakPtrFactory<DriveFileStreamReader> weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(DriveFileStreamReader);
 };
 
 }  // namespace drive
 
 #endif  // CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_FILE_STREAM_READER_H_