Revert of Don't use RSAPrivateKey in NSS integration code.

components/ownership/owner_key_util_impl.cc

Index: components/ownership/owner_key_util_impl.cc
diff --git a/components/ownership/owner_key_util_impl.cc b/components/ownership/owner_key_util_impl.cc
index cab5ffad2c759dc35ddc00cf211b37dc7b6438f8..bc7208e4642d21603513324d40236fddf4a4207c 100644
--- a/components/ownership/owner_key_util_impl.cc
+++ b/components/ownership/owner_key_util_impl.cc
@@ -8,12 +8,7 @@
 
 #include "base/files/file_util.h"
 #include "base/logging.h"
-
-#if defined(USE_NSS_CERTS)
-#include <keythi.h>
-#include "crypto/nss_key_util.h"
 #include "crypto/rsa_private_key.h"
-#endif
 
 namespace ownership {
 
@@ -59,18 +54,7 @@
 crypto::RSAPrivateKey* OwnerKeyUtilImpl::FindPrivateKeyInSlot(
     const std::vector<uint8>& key,
     PK11SlotInfo* slot) {
-  crypto::ScopedSECKEYPrivateKey private_key(
-      crypto::FindNSSKeyFromPublicKeyInfoInSlot(key, slot));
-  if (!private_key || SECKEY_GetPrivateKeyType(private_key.get()) != rsaKey)
-    return nullptr;
-#if defined(USE_OPENSSL)
-  // TODO(davidben): This assumes that crypto::RSAPrivateKey also uses NSS.
-  // https://crbug.com/478777
-  NOTIMPLEMENTED();
-  return nullptr;
-#else
-  return crypto::RSAPrivateKey::CreateFromKey(private_key.get());
-#endif
+  return crypto::RSAPrivateKey::FindFromPublicKeyInfoInSlot(key, slot);
 }
 #endif  // defined(USE_NSS_CERTS)