Fix the System Profile to not load extensions. It could otherwise be forced to by GPO.

chrome/browser/extensions/extension_system_impl.cc

Index: chrome/browser/extensions/extension_system_impl.cc
diff --git a/chrome/browser/extensions/extension_system_impl.cc b/chrome/browser/extensions/extension_system_impl.cc
index 1a295fc0aa0a1a04075414d788bda720dd1b7ae2..eabd3a91e7a5c75496ffc85ec41219d5bb7b3125 100644
--- a/chrome/browser/extensions/extension_system_impl.cc
+++ b/chrome/browser/extensions/extension_system_impl.cc
@@ -310,7 +310,8 @@ void ExtensionSystemImpl::Shared::Init(bool extensions_enabled) {
   // ExtensionService depends on RuntimeData.
   runtime_data_.reset(new RuntimeData(ExtensionRegistry::Get(profile_)));
 
-  bool autoupdate_enabled = !profile_->IsGuestSession();
+  bool autoupdate_enabled = !profile_->IsGuestSession() &&
+                            !profile_->IsSystemProfile();
 #if defined(OS_CHROMEOS)
   if (!extensions_enabled)
     autoupdate_enabled = false;