Hi, after a discussion with Jon, we decided that the usage of X-Device for CentralNotice platform-specific banners is a dead end. It has the following problems:<br>* X-Device was created for regulating frontend caching allowing some device/browser specific CSS. It was not intended for anything else.<br>




* It is not grouped by platform. Or browser type. It is grouped by cacheable entities.<br>* X-Device usage is dictated by performance. So if CN needs to distinguish between iPhone 4 and 5, for example, the answer will be &quot;no can do&quot;, we can&#39;t  increase cache fragmentation for the sake of banners.<br>


* We are working on decreasing the number of X-Devices: there&#39;s no guarantee that we will not merge &#39;android&#39; into &#39;webkit&#39; one day.<br>* Android-based browsers can correspond to &#39;android&#39;, &#39;webkit&#39;, &#39;operamini&#39; and &#39;operamobile&#39; X-Device strings, the latter 3 being shared with several other platforms. We in general need to target all Android users with our app banners, not users of a specific Android browser.<br>

<br>Thus, we decided to change it.<br>* <a href="https://gerrit.wikimedia.org/r/#/c/61989/">https://gerrit.wikimedia.org/r/#/c/61989/</a> removes <span class="wdd"><span class="str">wgMobileDeviceName support from MobileFrontend.<br>
* <a href="https://gerrit.wikimedia.org/r/#/c/61988/">https://gerrit.wikimedia.org/r/#/c/61988/</a> adds basic detection code to CentralNotice.<br><br>Ideally, every mobile banner could specify a user-agent regex and a special ResourceLoader module collect the regexes from all available banners.<br>
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