Modify U2F apdu classes to use unique pointers

device/u2f/u2f_apdu_fuzzer.cc

Index: device/u2f/u2f_apdu_fuzzer.cc
diff --git a/device/u2f/u2f_apdu_fuzzer.cc b/device/u2f/u2f_apdu_fuzzer.cc
index 809803c3fb6ac4bde5d5fe0c58378c2222d1257a..27a023dccc59cef725dfcbbc6f94bae4d31075aa 100644
--- a/device/u2f/u2f_apdu_fuzzer.cc
+++ b/device/u2f/u2f_apdu_fuzzer.cc
@@ -11,9 +11,9 @@
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   std::vector<uint8_t> input(data, data + size);
-  scoped_refptr<device::U2fApduCommand> cmd =
+  std::unique_ptr<device::U2fApduCommand> cmd =
       device::U2fApduCommand::CreateFromMessage(input);
-  scoped_refptr<device::U2fApduResponse> rsp =
+  std::unique_ptr<device::U2fApduResponse> rsp =
       device::U2fApduResponse::CreateFromMessage(input);
   return 0;
 }