This adds support for encrypted ONC import

crypto/hmac.cc

Index: crypto/hmac.cc
diff --git a/crypto/hmac.cc b/crypto/hmac.cc
index 9131313d9e0514d4a4794c40427213862dcd0104..c69eb3f838588364430acb88dc052b8943e99d79 100644
--- a/crypto/hmac.cc
+++ b/crypto/hmac.cc
@@ -8,9 +8,19 @@
 
 #include "base/logging.h"
 #include "crypto/secure_util.h"
+#include "crypto/symmetric_key.h"
 
 namespace crypto {
 
+bool HMAC::Init(SymmetricKey* key) {
+  std::string raw_key;
+  bool result = key->GetRawKey(&raw_key) && Init(raw_key);
+  // Zero out key copy.  This might get optimized away, but one can hope.
+  // Using std::string to store key info at all is a larger problem.
+  std::fill(raw_key.begin(), raw_key.end(), 0);
+  return result;
+}
+
 size_t HMAC::DigestLength() const {
   switch (hash_alg_) {
     case SHA1: