Update 1/6/15 - Added link to cumulative update that resolves this issue.
Update 12/27/14 - Added additional information on the change to Lync Web App.
Update 12/17/14 - Added link to KB article.
After applying the Lync Server 2013 December 2014 Cumulative Update, if a user using Google Chrome tries to use the Lync Web App to join a Lync meeting, they will get the following message:
Google Chrome no longer supports Lync Web App
Google is making multiple changes to the Chrome browser which affect the plug-in used by the Lync Web App (LWA) to provide a rich meeting experience including audio, video, and content sharing from the browser. These changes include discontinuing 32-bit Chrome support for Mac, and discontinuing support for the so-called "Netscape Plug-in API" (or NPAPI) commonly used by browser plugins. Microsoft is making changes to the Lync Web App to reduce the impact of these Google changes on our customers. For now, users will need to use Internet Explorer or Firefox if they would like to join the Lync meeting using Lync Web App.
This issue has been resolved in the latest cumulative update for Lync Server 2013. You can download the latest updates here.