Adding DRP specfic UMA for FirstContentfulPaint

content/child/web_url_loader_impl.cc

Index: content/child/web_url_loader_impl.cc
diff --git a/content/child/web_url_loader_impl.cc b/content/child/web_url_loader_impl.cc
index 639ded6578cef0430ef8ac37a7bf86e7f31f8b31..431bfb60d48cf531f683f88c9cee451b8c60f9ba 100644
--- a/content/child/web_url_loader_impl.cc
+++ b/content/child/web_url_loader_impl.cc
@@ -974,20 +974,21 @@ void WebURLLoaderImpl::PopulateURLResponse(const GURL& url,
       new WebURLResponseExtraDataImpl(info.npn_negotiated_protocol);
   response->setExtraData(extra_data);
   extra_data->set_was_fetched_via_spdy(info.was_fetched_via_spdy);
   extra_data->set_was_npn_negotiated(info.was_npn_negotiated);
   extra_data->set_was_alternate_protocol_available(
       info.was_alternate_protocol_available);
   extra_data->set_connection_info(info.connection_info);
   extra_data->set_was_fetched_via_proxy(info.was_fetched_via_proxy);
   extra_data->set_proxy_server(info.proxy_server);
   extra_data->set_is_using_lofi(info.is_using_lofi);
+  extra_data->set_used_data_reduction_proxy(info.used_data_reduction_proxy);
 
   // If there's no received headers end time, don't set load timing.  This is
   // the case for non-HTTP requests, requests that don't go over the wire, and
   // certain error cases.
   if (!info.load_timing.receive_headers_end.is_null()) {
     WebURLLoadTiming timing;
     PopulateURLLoadTiming(info.load_timing, &timing);
     const TimeTicks kNullTicks;
     timing.setWorkerStart(
         (info.service_worker_start_time - kNullTicks).InSecondsF());