Quickfix for URL preservation + combine_css conflict:

for now disable combine_css. Proper resolution (which will
make it win in some circumstances) will be a follow up,
but likely quite a bit more complex.
Note that combine_js isn't affected by this since it makes an entirely
new script element for combination (as well as new ones for evals), rather
than using the one from the first input.

Addresses Otto's reduction in issue #1215

Author: morlovich

net/instaweb/rewriter/css_combine_filter.cc

@@ -533,7 +533,12 @@ RewriteContext* CssCombineFilter::MakeRewriteContext() {
 }
 
 void CssCombineFilter::DetermineEnabled(GoogleString* disabled_reason) {
-  set_is_enabled(!driver()->flushed_cached_html());
+  if (driver()->options()->css_preserve_urls()) {
+    *disabled_reason = "Due to CSS URL preservation being on.";
+    set_is_enabled(false);
+  } else {
+    set_is_enabled(!driver()->flushed_cached_html());
+  }
 }
 
 }  // namespace net_instaweb

pagespeed/system/system_test.sh

@@ -597,6 +597,22 @@ if [ "$SECONDARY_HOSTNAME" != "" ]; then
     '.blue{foreground-color:blue}body{background:url(xarrow.png.pagespeed.' \
     '<style>.yellow{background-color:#ff0}</style>'
 
+  # Make sure that optimize for bandwidth + CombineCSS doesn't eat
+  # URLs.
+  URL=http://optimizeforbandwidth.example.com/mod_pagespeed_example
+  URL=$URL/combine_css.html?PageSpeedFilters=+combine_css
+  OUT=$(http_proxy=$SECONDARY_HOSTNAME \
+        $WGET -q -O - --header=X-PSA-Blocking-Rewrite:psatest $URL)
+  check_from "$OUT" fgrep -q bold.css
+
+  # Same for CombineJS --- which never actually did, to best of my knowledge,
+  # but better check just in case.
+  URL=http://optimizeforbandwidth.example.com/mod_pagespeed_example
+  URL=$URL/combine_javascript.html?PageSpeedFilters=+combine_javascript
+  OUT=$(http_proxy=$SECONDARY_HOSTNAME \
+        $WGET -q -O - --header=X-PSA-Blocking-Rewrite:psatest $URL)
+  check_from "$OUT" fgrep -q combine_javascript2
+
   # Test that we work fine with an explicitly configured SHM metadata cache.
   start_test Using SHM metadata cache
   HOST_NAME="http://shmcache.example.com"