Adjust to API change to InitiatePropertyCacheLookup

The last argument was not actually used, and hence was removed.

src/ngx_pagespeed.cc

@@ -1913,7 +1913,6 @@ ngx_int_t ps_resource_handler(ngx_http_request_t* r,
     driver->set_pagespeed_option_cookies(pagespeed_option_cookies);
 
     // TODO(jefftk): FlushEarlyFlow would go here.
-    bool page_callback_added = false;
     ProxyFetchPropertyCallbackCollector* property_callback =
         ProxyFetchFactory::InitiatePropertyCacheLookup(
             !html_rewrite /* is_resource_fetch */,
@@ -1921,8 +1920,7 @@ ngx_int_t ps_resource_handler(ngx_http_request_t* r,
             cfg_s->server_context,
             options,
             ctx->base_fetch,
-            false /* requires_blink_cohort (no longer unused) */,
-            &page_callback_added);
+            false /* requires_blink_cohort (no longer unused) */);
 
     // Will call StartParse etc.  The rewrite driver will take care of deleting
     // itself if necessary.