Pass slot id to Shill for manually configured WiFi with EAP-TLS.

chrome/browser/chromeos/options/cert_library.h

Index: chrome/browser/chromeos/options/cert_library.h
diff --git a/chrome/browser/chromeos/options/cert_library.h b/chrome/browser/chromeos/options/cert_library.h
index eb9b7e538523f7587bb4237e6c1e116cbf79ca4c..e5d1cb0aca75765feb511dc411363345f4b3d538 100644
--- a/chrome/browser/chromeos/options/cert_library.h
+++ b/chrome/browser/chromeos/options/cert_library.h
@@ -63,6 +63,9 @@ class CertLibrary : public CertLoader::Observer {
   // Returns true if the TPM is available for hardware-backed certificates.
   bool IsHardwareBacked() const;
 
+  // Returns the id of the slot that contains the user certificates.
+  std::string GetTPMSlotID() const;
+
   // Retruns the number of certificates available for |type|.
   int NumCertificates(CertType type) const;