Sites with HTTPS users and no HTTPS mod_pagespeed configuration get log spew

[GoogleCodeExporter]

Prior to 0.10.19.*, mod_pagespeed would never initiate a rewrite for HTTPS 
resource because CreateInputResource would return NULL based on the scheme of 
the resource.

Now it will go through the entire rewriting flow until the fetch.  The fetcher 
will fail reasonably fast, but at a minimum it will log the failure in 
error.log, which causes system load.

I think we can get back to a situation where there's a pretty fast failure 
earlier in the flow, if we do something like this:

1. Add "bool UrlAsyncFetcher::SupportsHttps(), base-class returns false.  
Existing fetchers will not override.  Alternatively, have "bool 
UrlAsyncFetcher::PrevalidateUrl(const GoogleUrl&)", base-class checks 
.scheme=="http".  It could also check the syntax of the domain & the req 
headers or something; not sure what's best here.  The idea here is that this is 
a syntax check: no system-calls should be made or threads should be spawned.

2. CreateInputResource will do an origin-map / lookup in LoadFromFile map, and 
determine whether we'd ever be able to fetch such a resource using 
PrevalidateUrl or SupportsHttps.

Original issue reported on code.google.com by jmara...@google.com on 5 Dec 2011 at 2:12