Adds the new URLRequest::OnBeforeNetworkStart hook to the

content/browser/loader/async_resource_handler.cc

Index: content/browser/loader/async_resource_handler.cc
diff --git a/content/browser/loader/async_resource_handler.cc b/content/browser/loader/async_resource_handler.cc
index 93d7e839aa2d7af1b4c1507a447fa018de89a180..52c1d8fd251d089c57fd2f37405afd89f688ea32 100644
--- a/content/browser/loader/async_resource_handler.cc
+++ b/content/browser/loader/async_resource_handler.cc
@@ -220,6 +220,12 @@ bool AsyncResourceHandler::OnWillStart(int request_id,
   return true;
 }
 
+bool AsyncResourceHandler::OnBeforeNetworkStart(int request_id,
+                                                const GURL& url,
+                                                bool* defer) {
+  return true;
+}
+
 bool AsyncResourceHandler::OnWillRead(int request_id,
                                       scoped_refptr<net::IOBuffer>* buf,
                                       int* buf_size,