drive: Fix DriveFileStreamReader to run cancel closure on the right thread

chrome/browser/chromeos/drive/drive_file_stream_reader.cc

Index: chrome/browser/chromeos/drive/drive_file_stream_reader.cc
diff --git a/chrome/browser/chromeos/drive/drive_file_stream_reader.cc b/chrome/browser/chromeos/drive/drive_file_stream_reader.cc
index 8f4776b6c78cb3a4d32f96019f5ee2ff8e2ccb6e..4a5530fed586ac4612851e83dd35f89a310901ba 100644
--- a/chrome/browser/chromeos/drive/drive_file_stream_reader.cc
+++ b/chrome/browser/chromeos/drive/drive_file_stream_reader.cc
@@ -360,7 +360,7 @@ void DriveFileStreamReader::InitializeAfterGetFileContentInitialized(
     // needed and and invalidate weak pointers so that we won't
     // receive unwanted callbacks.
     if (!ui_cancel_download_closure.is_null())
-      ui_cancel_download_closure.Run();
+      RunTaskOnUIThread(ui_cancel_download_closure);
     weak_ptr_factory_.InvalidateWeakPtrs();
     callback.Run(
         net::ERR_REQUEST_RANGE_NOT_SATISFIABLE, scoped_ptr<ResourceEntry>());