Extension docs: Cleanup after there's only one version.

chrome/common/extensions/docs/templates/articles/app_csp.html

 <h1>Comply with CSP</h1>
 
 
 <p>
 If you're unfamiliar with Content Security Policy (CSP),
 <a href="http://www.html5rocks.com/en/tutorials/security/content-security-policy/">An Introduction to Content Security Policy</a>
 is a good starting point.
 It covers the broader web platform view of CSP;
 packaged apps CSP isn't as flexible.
 You should read the
-<a href="http://code.google.com/chrome/extensions/contentSecurityPolicy.html">Chrome extension Content Security Policy</a>
+<a href="/extensions/contentSecurityPolicy.html">Chrome extension Content Security Policy</a>
 as it's the foundation for the packaged app CSP.
 For brevity's sake,
 we don't repeat the same information here.
 </p>
 
 <p>
 CSP is a policy to mitigate against cross-site scripting issues,
 and we all know that cross-scripting is bad.
 We aren’t going to try and convince you
 that CSP is a warm-and-fuzzy new policy.
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 <h3 id="embed_content">Embed web content</h3>
 
 <p>
 Instead of using an iframe,
 you can call out to an external URL using an object tag
 (see <a href="app_external.html#webview">Embed external web pages</a>).
 </p>
 
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