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..cfa395837dc3df9d3713e0e866c9c55d53558e9a 100644
--- a/crypto/hmac.cc
+++ b/crypto/hmac.cc
@@ -8,9 +8,23 @@
 
 #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 probably just gets optimized away,
+  // but one can hope.  Using std::string to store key info at all is a larger
+  // problem. This trys to keep the fill call from being optimized away by
+  // creating an alias to internal data with a volatile.
+  volatile char *optimization_blocker = const_cast<char*>(raw_key.data());
+  std::fill(raw_key.begin(), raw_key.end(), 0);
+  optimization_blocker = NULL;
+  return result;
+}
+
 size_t HMAC::DigestLength() const {
   switch (hash_alg_) {
     case SHA1: