need a way to selectively keep some comments

[GoogleCodeExporter]

some google services rely on some specific comments to better interpret 
(semantically) the content of web pages.

for example, the google-adsense crawler (user-agent Mediapartner-Google) uses 
the comments:

<!-- google_ad_section_start(weight=ignore) --> 
...
<!-- google_ad_section_end --> 

and

<!-- google_ad_section_start --> 
...
<!-- google_ad_section_end --> 

to ignore (or to put emphasis on) some sections of text for better targeting 
advertising that should be related to the significant content of the page.

see adsense section targeting:
https://www.google.com/adsense/support/bin/answer.py?hl=en&answer=23168

stripping those comments would cause lower quality ad targeting in pages using 
google adsense.

so mod_pagespeed should have a way to selectively keep some particular comments 
(e.g. a text file that contains the comments to keep).

Original issue reported on code.google.com by loupi...@gmail.com on 12 Mar 2011 at 3:30