Allow chrome files to touch implicit XPCNativeWrappers. bug 387084, r+sr=jst

    return JS_TRUE;

  }

  XPCCallContext ccx(JS_CALLER, cx);

  nsIXPCSecurityManager *sm = ccx.GetXPCContext()->

    GetAppropriateSecurityManager(nsIXPCSecurityManager::HOOK_CALL_METHOD);

  nsCOMPtr<nsIScriptSecurityManager> ssm(do_QueryInterface(sm));

  // A last ditch effort to allow access: if the subject principal is

  // the system principal, then some XPCNativeWrapper-using code has

  // passed one into other code. If that other code is chrome, then

  // allow access.

  PRBool isSystem;

  nsresult rv = ssm->SubjectPrincipalIsSystem(&isSystem);

  if (NS_SUCCEEDED(rv) && isSystem) {

    return JS_TRUE;

  }

  // Otherwise, we're looking at a non-system file with a handle on an

  // implicit wrapper. This is a bug! Deny access.

  return ThrowException(NS_ERROR_XPC_SECURITY_MANAGER_VETO, cx);