diff --git a/example/wvpl_cas_proxy_environment_example b/example/wvpl_cas_proxy_environment_example
index fb7149d..4ccd1b5 100644
Binary files a/example/wvpl_cas_proxy_environment_example and b/example/wvpl_cas_proxy_environment_example differ
diff --git a/example/wvpl_cas_proxy_session_example b/example/wvpl_cas_proxy_session_example
index ee2a968..b12085d 100644
Binary files a/example/wvpl_cas_proxy_session_example and b/example/wvpl_cas_proxy_session_example differ
diff --git a/libwvpl_cas_proxy.so b/libwvpl_cas_proxy.so
index 66e0ff6..65485a8 100755
Binary files a/libwvpl_cas_proxy.so and b/libwvpl_cas_proxy.so differ
diff --git a/media_cas_proxy_sdk/external/common/wvpl/wvpl_cas_proxy_session.h b/media_cas_proxy_sdk/external/common/wvpl/wvpl_cas_proxy_session.h
index 9fadd05..41af1a9 100644
--- a/media_cas_proxy_sdk/external/common/wvpl/wvpl_cas_proxy_session.h
+++ b/media_cas_proxy_sdk/external/common/wvpl/wvpl_cas_proxy_session.h
@@ -9,11 +9,18 @@
 #ifndef MEDIA_CAS_PROXY_SDK_EXTERNAL_COMMON_WVPL_WVPL_CAS_PROXY_SESSION_H_
 #define MEDIA_CAS_PROXY_SDK_EXTERNAL_COMMON_WVPL_WVPL_CAS_PROXY_SESSION_H_
 
+#include <memory>
 #include <string>
 #include <vector>
-#include "absl/synchronization/mutex.h"
 #include "sdk/external/common/wvpl/wvpl_sdk_session.h"
-#include "protos/public/media_cas_license.pb.h"
+
+namespace absl {
+class Mutex;
+}  // namespace absl
+
+namespace widevine {
+class CasDrmLicenseRequest;
+}  // namespace widevine
 
 namespace widevine_server {
 namespace wv_pl_sdk {
@@ -48,7 +55,7 @@ constexpr uint32_t kRelease = 2;
  */
 class WvPLCASProxySession : public WvPLSDKSession {
  public:
-  ~WvPLCASProxySession() override {}
+  ~WvPLCASProxySession() override;
 
   /**
    * Returns a std::string containing the version in the form -
@@ -101,10 +108,10 @@ class WvPLCASProxySession : public WvPLSDKSession {
   std::string provider_;
 
   // holds all the WvPLCasKey objects.  Used when generating a CAS License.
-  std::vector<WvPLCasKey> cas_keys_ GUARDED_BY(cas_keys_mutex_);
+  std::vector<WvPLCasKey> cas_keys_;
 
-  // Mutex to protect the keys owned by this session.
-  mutable absl::Mutex cas_keys_mutex_;
+  // Mutex to protect the keys, |cas_keys_|, owned by this session.
+  mutable std::unique_ptr<absl::Mutex> cas_keys_mutex_;
 };
 
 }  // namespace wv_pl_sdk