Implement symmetric key for openssl

base/crypto/symmetric_key.h

Index: base/crypto/symmetric_key.h
diff --git a/base/crypto/symmetric_key.h b/base/crypto/symmetric_key.h
index 3f2be76390c7188a5ec446dd1a79aa95b575f1ab..5958ec0f7ecb2a30872ff1b15c8fe093e2451e09 100644
--- a/base/crypto/symmetric_key.h
+++ b/base/crypto/symmetric_key.h
@@ -66,8 +66,9 @@ class SymmetricKey {
 
  private:
 #if defined(USE_OPENSSL)
-  // TODO(joth): Add a constructor that accepts OpenSSL symmetric key data, and
-  // the appropriate data members to store it in.
+  // Swaps in the content of the |key|.
+  explicit SymmetricKey(std::string* key);
+  std::string key_;
 #elif defined(USE_NSS)
   explicit SymmetricKey(PK11SymKey* key);
   ScopedPK11SymKey key_;