Remove deprecated base::NonThreadSafe in media/cast.

media/cast/common/transport_encryption_handler.h

Index: media/cast/common/transport_encryption_handler.h
diff --git a/media/cast/common/transport_encryption_handler.h b/media/cast/common/transport_encryption_handler.h
index 053d5d730712da21ba825b267f5b9ec2d817700b..ab3667cdc8ceb92868eabefde3033e6334c32dae 100644
--- a/media/cast/common/transport_encryption_handler.h
+++ b/media/cast/common/transport_encryption_handler.h
@@ -14,7 +14,6 @@
 
 #include "base/macros.h"
 #include "base/strings/string_piece.h"
-#include "base/threading/non_thread_safe.h"
 #include "media/cast/common/frame_id.h"
 
 namespace crypto {
@@ -25,7 +24,7 @@ class SymmetricKey;
 namespace media {
 namespace cast {
 
-class TransportEncryptionHandler : public base::NonThreadSafe {
+class TransportEncryptionHandler {
  public:
   TransportEncryptionHandler();
   ~TransportEncryptionHandler();