You're missing a question mark after the chunk name:
[[$chunk_story_page_extra? &title=`[[+title]]` &content=`[[+content]]`]]
You could also do this, might be slightly more efficient too:
$array = array(
'id' => 1,
'title' => 'Title of Story',
'content' => 'Content of story...'
);
$array['chunk_story_page_extra'] = $modx->getChunk('chunk_story_page_extra', $array);
echo $modx->getChunk('chunk_story_page', $array);
And in your chunk:
[[+chunk_story_page_extra]]
<div class="story">
<h1>[[+title]]</h1>
<div class="content">
[[+content]]
</div>
</div>