Save the files in empty directory, which should not be deleted while this extension in use (eg. directory "Empty new tab page" in Documents ) and:
- Go to Chrome Extensions page (chrome://extensions/)
- Check "Developer mode" (upper right)
- Click "Load unpacked extension..." and point to the directory where two files was saved Developer mode now could be turned off.
Now we've got absolutely blank new tab with absolutely blank URL field.
Note: newtab.html could be customized in a suitable way.