Update TPMTokenLoader class comment.

chromeos/tpm_token_loader.h

Index: chromeos/tpm_token_loader.h
diff --git a/chromeos/tpm_token_loader.h b/chromeos/tpm_token_loader.h
index 9ac7a61e61df4adfc9b5636c31771a2c35fcd190..ffd7907d47cde18d32f6c40774fb38e1df7ff1f8 100644
--- a/chromeos/tpm_token_loader.h
+++ b/chromeos/tpm_token_loader.h
@@ -23,11 +23,13 @@ class SequencedTaskRunner;
 
 namespace chromeos {
 
-// This class is responsible for loading the TPM token when the user logs
-// in. It is expected to be constructed on the UI thread and public methods
-// should all be called from the UI thread. When the TPM token is loaded,
-// or if the TPM should stay disabled for the session, the observers are
-// notified using |OnTPMTokenReady|.
+// This class is responsible for loading the TPM backed token for the system
+// slot when the user logs in. It is expected to be constructed on the UI thread
+// and public methods should all be called from the UI thread.
+// When the TPM token is loaded, or if the TPM should stay disabled for the
+// session, the observers are notified using |OnTPMTokenReady|.
+// Note: This currently initializes the token with the hard coded default id 0.
+// See CryptohomeClient::OnPkcs11GetTpmTokenInfo.
 class CHROMEOS_EXPORT TPMTokenLoader : public LoginState::Observer {
  public:
   class Observer {