drive: Return cancel closure from FileSystem::GetFileContent

chrome/browser/chromeos/drive/drive_file_stream_reader.h

Index: chrome/browser/chromeos/drive/drive_file_stream_reader.h
diff --git a/chrome/browser/chromeos/drive/drive_file_stream_reader.h b/chrome/browser/chromeos/drive/drive_file_stream_reader.h
index c39f2853d039736f82c02e23ab8e75f900c1411b..b6a2b1d3bf9841cb9fa6ef68002578e4ffa63b2f 100644
--- a/chrome/browser/chromeos/drive/drive_file_stream_reader.h
+++ b/chrome/browser/chromeos/drive/drive_file_stream_reader.h
@@ -172,15 +172,17 @@ class DriveFileStreamReader {
            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(
@@ -201,6 +203,7 @@ class DriveFileStreamReader {
 
   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