drive: Return cancel closure from FileSystem::GetFileContent

chrome/browser/chromeos/drive/file_system.cc

 // 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.
 
 #include "chrome/browser/chromeos/drive/file_system.h"
 
 #include "base/bind.h"
 #include "base/file_util.h"
 #include "base/platform_file.h"
 #include "base/prefs/pref_service.h"
@@ skipping 594 matching lines @@
 }
 
 void FileSystem::GetFileForSaving(const base::FilePath& file_path,
                                   const GetFileCallback& callback) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(!callback.is_null());
 
   get_file_for_saving_operation_->GetFileForSaving(file_path, callback);
 }
 
-void FileSystem::GetFileContent(
+base::Closure FileSystem::GetFileContent(
     const base::FilePath& file_path,
     const GetFileContentInitializedCallback& initialized_callback,
     const google_apis::GetContentCallback& get_content_callback,
     const FileOperationCallback& completion_callback) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(!initialized_callback.is_null());
   DCHECK(!get_content_callback.is_null());
   DCHECK(!completion_callback.is_null());
 
-  download_operation_->EnsureFileDownloadedByPath(
+  return download_operation_->EnsureFileDownloadedByPath(
       file_path,
       ClientContext(USER_INITIATED),
       initialized_callback,
       get_content_callback,
       base::Bind(&GetFileCallbackToFileOperationCallbackAdapter,
                  completion_callback));
 }
 
 void FileSystem::GetResourceEntry(
     const base::FilePath& file_path,
@@ skipping 383 matching lines @@
       FROM_HERE,
       base::Bind(&GetPathFromResourceIdOnBlockingPool,
                  resource_metadata_,
                  resource_id,
                  file_path),
       base::Bind(&GetPathFromResourceIdAfterGetPath,
                  base::Owned(file_path),
                  callback));
 }
 }  // namespace drive