Replace some hard coded schemes with the constants in /url/url_constants.h.

content/browser/loader/resource_dispatcher_host_impl.cc

Index: content/browser/loader/resource_dispatcher_host_impl.cc
diff --git a/content/browser/loader/resource_dispatcher_host_impl.cc b/content/browser/loader/resource_dispatcher_host_impl.cc
index 7b09885c9f353f06f9c4158acf0ada39e32c0240..c49bfe9a4c3b6431a9fe5a5ae1210af8e5608e0f 100644
--- a/content/browser/loader/resource_dispatcher_host_impl.cc
+++ b/content/browser/loader/resource_dispatcher_host_impl.cc
@@ -745,7 +745,7 @@ void ResourceDispatcherHostImpl::DidReceiveResponse(ResourceLoader* loader) {
 
   if (loader->request()->was_fetched_via_proxy() &&
       loader->request()->was_fetched_via_spdy() &&
-      loader->request()->url().SchemeIs("http")) {
+      loader->request()->url().SchemeIs(url::kHttpScheme)) {
     scheduler_->OnReceivedSpdyProxiedHttpResponse(
         info->GetChildID(), info->GetRouteID());
   }