drive: Use OperationTestBase from CreateDirectoryOperationTest

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

Index: chrome/browser/chromeos/drive/file_system/create_directory_operation.h
diff --git a/chrome/browser/chromeos/drive/file_system/create_directory_operation.h b/chrome/browser/chromeos/drive/file_system/create_directory_operation.h
index 330945733578de31c939c2e0925714e04a60c8d8..427279a435ad9a2ed485ed33b0ee36af58aa132d 100644
--- a/chrome/browser/chromeos/drive/file_system/create_directory_operation.h
+++ b/chrome/browser/chromeos/drive/file_system/create_directory_operation.h
@@ -58,17 +58,16 @@ class CreateDirectoryOperation {
                        bool is_recursive,
                        const FileOperationCallback& callback);
 
+ private:
   // Returns the file path to the existing deepest directory, which appears
   // in the |file_path|, with |entry| storing the directory's resource entry.
   // If not found, returns an empty file path.
   // This should run on |blocking_task_runner_|.
-  // This is public for testing.
   static base::FilePath GetExistingDeepestDirectory(
       internal::ResourceMetadata* metadata,
       const base::FilePath& directory_path,
       ResourceEntry* entry);
 
- private:
   // Part of CreateDirectory(). Called after GetExistingDeepestDirectory
   // is completed.
   void CreateDirectoryAfterGetExistingDeepestDirectory(