shill: vpn: Implement NSS database interface class.

Use the NSS class to lookup NSS certificates for OpenVPN.

BUG=chromium-os:28792
TEST=unit tests

Change-Id: I2e0c7924d664f375f5b01bc73506e2b91e6f8720
Reviewed-on: https://gerrit.chromium.org/gerrit/19457
Tested-by: Darin Petkov <petkov@chromium.org>
Reviewed-by: Paul Stewart <pstew@chromium.org>
Commit-Ready: Darin Petkov <petkov@chromium.org>
diff --git a/shill_daemon.h b/shill_daemon.h
index 76737bc..48a35ed 100644
--- a/shill_daemon.h
+++ b/shill_daemon.h
@@ -21,6 +21,7 @@
 class ControlInterface;
 class DHCPProvider;
 class GLib;
+class NSS;
 class ProxyFactory;
 class RoutingTable;
 class RTNLHandler;
@@ -32,8 +33,7 @@
 
   void AddDeviceToBlackList(const std::string &device_name);
   void SetStartupProfiles(const std::vector<std::string> &profile_path);
-  // Main for connection manager.  Starts main process and holds event
-  // loop.
+  // Main for connection manager.  Starts main process and holds event loop.
   void Run();
   void Quit();
 
@@ -46,6 +46,7 @@
   Config *config_;
   ControlInterface *control_;
   Metrics metrics_;
+  NSS *nss_;
   ProxyFactory *proxy_factory_;
   RTNLHandler *rtnl_handler_;
   RoutingTable *routing_table_;