Add update observer to file_system_operation_impl_unittest for

storage/browser/fileapi/file_system_operation_runner.cc

Index: storage/browser/fileapi/file_system_operation_runner.cc
diff --git a/storage/browser/fileapi/file_system_operation_runner.cc b/storage/browser/fileapi/file_system_operation_runner.cc
index 46e662a428d516fd58836ce00bc7ec42a61d3ccd..018961ba73df4babb958aff02b163c2fcfdb66b0 100644
--- a/storage/browser/fileapi/file_system_operation_runner.cc
+++ b/storage/browser/fileapi/file_system_operation_runner.cc
@@ -422,6 +422,7 @@ OperationID FileSystemOperationRunner::RemoveFile(
     DidFinish(handle, callback, error);
     return handle.id;
   }
+  PrepareForWrite(handle.id, url);
   operation->RemoveFile(
       url,
       base::Bind(&FileSystemOperationRunner::DidFinish, AsWeakPtr(),
@@ -441,6 +442,7 @@ OperationID FileSystemOperationRunner::RemoveDirectory(
     DidFinish(handle, callback, error);
     return handle.id;
   }
+  PrepareForWrite(handle.id, url);
   operation->RemoveDirectory(
       url,
       base::Bind(&FileSystemOperationRunner::DidFinish, AsWeakPtr(),