Why Google Search Results are not Filtered on Chrome(ium)?
Update from August, 2017. Support for SDCH protocol is disabled in Chrome/Chromium versions 59+. The following steps are no longer required. See https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/nQl0ORHy7sw for more information.
To speed up search results Google Chrome may use the SDCH protocol (Shared Dictionary Compression over HTTP). This protocol lets server and browser limit the amount of exchanged textual information by transferring only differences between two versions of the server’s content. See http://prxbx.com/forums/showthread.php?tid=1379 and http://blog.endpoint.com/2009/07/sdch-shared-dictionary-compression-over.html for more detailed discussion.
This may lead to a situation when first portion of search results is scanned by the adult language module of Web Safety and is considered appropriate as the calculated weight of all words is lower than the limit. It may also happen that the next portion of transferred text is marked as appropriate too. The browser later will merge these two portions together and produce a way too inappropriate page.
In order to mitigate this problem it is recommended to add the following setting to your Squid configuration file:
request_header_access Avail-Dictionary deny all
Please understand that it may have negative effects on the speed of search results display and may possibly lead to some unexpected errors on search pages on Google servers.