Use nogncheck for content/browser/site_instance_impl.h

This is needed because  //content/browser:browser is not a visible target

shell/browser/electron_browser_client.cc

@@ -30,6 +30,7 @@
 #include "chrome/common/chrome_version.h"
 #include "components/net_log/chrome_net_log.h"
 #include "components/network_hints/common/network_hints.mojom.h"
+#include "content/browser/site_instance_impl.h"  // nogncheck
 #include "content/public/browser/browser_main_runner.h"
 #include "content/public/browser/browser_ppapi_host.h"
 #include "content/public/browser/browser_task_traits.h"