Initialize per-ChromeOS-user NSS slots and provide the functions to access them.

crypto/nss_util.h

Index: crypto/nss_util.h
diff --git a/crypto/nss_util.h b/crypto/nss_util.h
index 2c825a05eb87289ea8651da974f5ef05124a1fb6..83a8b076739a54012809d914374a3ac9bf9c715e 100644
--- a/crypto/nss_util.h
+++ b/crypto/nss_util.h
@@ -7,6 +7,7 @@
 
 #include <string>
 #include "base/basictypes.h"
+#include "base/callback_forward.h"
 #include "crypto/crypto_export.h"
 
 namespace base {
@@ -102,6 +103,9 @@ CRYPTO_EXPORT void OpenPersistentNSSDB();
 // GetPrivateNSSKeySlot() will return the TPM slot if one was found.
 CRYPTO_EXPORT void EnableTPMTokenForNSS();
 
+// Returns true if EnableTPMTokenForNSS has been called.
+CRYPTO_EXPORT bool IsTPMTokenEnabledForNSS();
+
 // Get name and user PIN for the built-in TPM token on ChromeOS.
 // Either one can safely be NULL.  Should only be called after
 // EnableTPMTokenForNSS has been called with a non-null delegate.
@@ -114,6 +118,10 @@ CRYPTO_EXPORT void GetTPMTokenInfo(std::string* token_name,
 // loaded into NSS.
 CRYPTO_EXPORT bool IsTPMTokenReady();
 
+// Register a callback to be run when the TPM module is loaded.
+// If the module is already loaded, the |callback| will be run synchronously.
+CRYPTO_EXPORT void OnTPMReady(const base::Closure& callback);

[Ryan Sleevi, 2013/11/27 00:24:11]

My perhaps incorrect believe is that "|callback| will be run synchronously" is
often an anti-pattern - or at least, a surprise to most people when writing
code.

It can have all sorts of unintended side-effects, from recursion issues to
premature deletion. I've seen enough code go by that uses this that ends up
being bugged that I wonder whether it makes more sense to use:

CRYPTO_EXPORT bool IsTPMModuleReady(const base::Closure& callback);

It's also not clear how this is different from line 115-119.

[mattm, 2013/11/27 04:12:23]

Ok. I guess I liked how it resulted in less duplication, but making it harder to
mess up is reasonable. Changed.

+
 // Initialize the TPM token.  Does nothing if it is already initialized.
 CRYPTO_EXPORT bool InitializeTPMToken(const std::string& token_name,
                                       int token_slot_id,