Use std::move for key strings.

[ Cherry-pick of v19 http://go/wvgerrit/219351 ]
[ Merge of http://go/wvgerrit/219455 ]

Coverity discovered an oppertunity to use the C++'s move semantics
for the prov 4.0 keys.  A similar possibility was available for the
matching wrapped key.  The CryptoWrappedKey class was updated to
enable moving of the wrapped key as well.

Bug: 406539167
Bug: 391469176
Change-Id: I7d76013638c220fc81d6d9c42add2516abd7374a

libwvdrmengine/cdm/core/include/crypto_wrapped_key.h

@@ -5,6 +5,7 @@
 #define WVCDM_CORE_CRYPTO_WRAPPED_KEY_H_
 
 #include <string>
+#include <utility>
 
 namespace wvcdm {
 
@@ -18,6 +19,8 @@ class CryptoWrappedKey {
   CryptoWrappedKey() {}
   CryptoWrappedKey(Type type, const std::string& key)
       : type_(type), key_(key) {}
+  CryptoWrappedKey(Type type, std::string&& key)
+      : type_(type), key_(std::move(key)) {}
 
   Type type() const { return type_; }
   void set_type(Type type) { type_ = type; }
@@ -26,6 +29,7 @@ class CryptoWrappedKey {
   // Mutable reference getter for passing to OMECrypto.
   std::string& key() { return key_; }
   void set_key(const std::string& key) { key_ = key; }
+  void set_key(std::string&& key) { key_ = std::move(key); }
 
   void Clear() {
     type_ = kUninitialized;

libwvdrmengine/cdm/core/src/certificate_provisioning.cpp

@@ -651,10 +651,10 @@ CdmResponseType CertificateProvisioning::GetProvisioning40RequestInternal(
   // Need the wrapped Prov 4.0 private key to store once the response
   // is received.  The wrapped key is not available in the response.
   prov40_wrapped_private_key_ =
-      CryptoWrappedKey(private_key_type, wrapped_private_key);
+      CryptoWrappedKey(private_key_type, std::move(wrapped_private_key));
   // Store the public key from the request.  This is used to match
   // up the response with the most recently generated request.
-  prov40_public_key_ = public_key;
+  prov40_public_key_ = std::move(public_key);
 
   state_ = is_oem_prov_request ? kOemRequestSent : kDrmRequestSent;
   return CdmResponseType(NO_ERROR);