Make crypto::GetSystemNSSKeySlot asynchronous.

The system slot is set asynchronously, so the getting the system slot should happen asynchronously as well.

BUG=210525
TBR=rsleevi@chromium.org

Review URL: https://codereview.chromium.org/426983002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@286493 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 26 insertions, 12 deletions

diff --git a/crypto/nss_util.cc b/crypto/nss_util.cc
index 64489dc..96c13e2 100644
--- a/crypto/nss_util.cc
+++ b/crypto/nss_util.cc
@@ -594,18 +594,29 @@ class NSSInitSingleton {
 #endif
 
 #if defined(OS_CHROMEOS)
-  PK11SlotInfo* GetSystemNSSKeySlot() {
-    DCHECK(thread_checker_.CalledOnValidThread());
+  void GetSystemNSSKeySlotCallback(
+      const base::Callback<void(ScopedPK11Slot)>& callback) {
+    callback.Run(ScopedPK11Slot(PK11_ReferenceSlot(tpm_slot_)));
+  }
 
+  ScopedPK11Slot GetSystemNSSKeySlot(
+      const base::Callback<void(ScopedPK11Slot)>& callback) {
+    DCHECK(thread_checker_.CalledOnValidThread());
     // TODO(mattm): chromeos::TPMTokenloader always calls
     // InitializeTPMTokenAndSystemSlot with slot 0.  If the system slot is
     // disabled, tpm_slot_ will be the first user's slot instead. Can that be
     // detected and return NULL instead?
-    if (tpm_token_enabled_for_nss_ && IsTPMTokenReady(base::Closure()))
-      return PK11_ReferenceSlot(tpm_slot_);
-    // If we were supposed to get the hardware token, but were
-    // unable to, return NULL rather than fall back to sofware.
-    return NULL;
+
+    base::Closure wrapped_callback;
+    if (!callback.is_null()) {
+      wrapped_callback =
+          base::Bind(&NSSInitSingleton::GetSystemNSSKeySlotCallback,
+                     base::Unretained(this) /* singleton is leaky */,
+                     callback);
+    }
+    if (IsTPMTokenReady(wrapped_callback))
+      return ScopedPK11Slot(PK11_ReferenceSlot(tpm_slot_));
+    return ScopedPK11Slot();
   }
 #endif
 
@@ -1000,8 +1011,9 @@ AutoSECMODListReadLock::~AutoSECMODListReadLock() {
 #endif  // defined(USE_NSS)
 
 #if defined(OS_CHROMEOS)
-PK11SlotInfo* GetSystemNSSKeySlot() {
-  return g_nss_singleton.Get().GetSystemNSSKeySlot();
+ScopedPK11Slot GetSystemNSSKeySlot(
+    const base::Callback<void(ScopedPK11Slot)>& callback) {
+  return g_nss_singleton.Get().GetSystemNSSKeySlot(callback);
 }
 
 void SetSystemKeySlotForTesting(ScopedPK11Slot slot) {
diff --git a/crypto/nss_util_internal.h b/crypto/nss_util_internal.h
index c40295f..cb1b9bd 100644
--- a/crypto/nss_util_internal.h
+++ b/crypto/nss_util_internal.h
@@ -47,9 +47,11 @@ class CRYPTO_EXPORT AutoSECMODListReadLock {
 };
 
 #if defined(OS_CHROMEOS)
-// Returns a reference to the system-wide TPM slot. Caller must release returned
-// reference with PK11_FreeSlot.
-CRYPTO_EXPORT PK11SlotInfo* GetSystemNSSKeySlot() WARN_UNUSED_RESULT;
+// Returns a reference to the system-wide TPM slot if it is loaded. If it is not
+// loaded and |callback| is non-null, the |callback| will be run once the slot
+// is loaded.
+CRYPTO_EXPORT ScopedPK11Slot GetSystemNSSKeySlot(
+    const base::Callback<void(ScopedPK11Slot)>& callback) WARN_UNUSED_RESULT;
 
 // Sets the test system slot. If this was called before
 // InitializeTPMTokenAndSystemSlot and no system token is provided by the Chaps