Extract GetResolveFile into DownloadOperation.

chrome/browser/chromeos/drive/file_system/drive_operations.h

Index: chrome/browser/chromeos/drive/file_system/drive_operations.h
diff --git a/chrome/browser/chromeos/drive/file_system/drive_operations.h b/chrome/browser/chromeos/drive/file_system/drive_operations.h
index 84e5a9975242be8b72e75a5072bc501da4e90b06..3b6b1d69eb9d5b3d68452f3a1b93878dbf808a16 100644
--- a/chrome/browser/chromeos/drive/file_system/drive_operations.h
+++ b/chrome/browser/chromeos/drive/file_system/drive_operations.h
@@ -31,6 +31,7 @@ namespace file_system {
 class CopyOperation;
 class CreateDirectoryOperation;
 class CreateFileOperation;
+class DownloadOperation;
 class MoveOperation;
 class OperationObserver;
 class RemoveOperation;
@@ -111,6 +112,15 @@ class DriveOperations {
               bool is_recursive,
               const FileOperationCallback& callback);
 
+  // Wrapper function for download_operation_.
+  // |completion_callback| must not be null.
+  void EnsureFileDownloaded(
+      const base::FilePath& file_path,
+      DriveClientContext context,
+      const GetFileContentInitializedCallback& initialized_callback,
+      const google_apis::GetContentCallback& get_content_callback,
+      const GetFileCallback& completion_callback);
+
   // Wrapper function for update_operation_.
   // |callback| must not be null.
   void UpdateFileByResourceId(const std::string& resource_id,
@@ -129,6 +139,7 @@ class DriveOperations {
   scoped_ptr<CreateFileOperation> create_file_operation_;
   scoped_ptr<MoveOperation> move_operation_;
   scoped_ptr<RemoveOperation> remove_operation_;
+  scoped_ptr<DownloadOperation> download_operation_;
   scoped_ptr<UpdateOperation> update_operation_;
   scoped_ptr<SearchOperation> search_operation_;
 };