Modify U2F apdu classes to use unique pointers

device/u2f/u2f_apdu_response.h

Index: device/u2f/u2f_apdu_response.h
diff --git a/device/u2f/u2f_apdu_response.h b/device/u2f/u2f_apdu_response.h
index a52faf1e945d24f0a832943e42dd610443ca296f..44bf7d61af1825c75d31a0b838373b67d0de339d 100644
--- a/device/u2f/u2f_apdu_response.h
+++ b/device/u2f/u2f_apdu_response.h
@@ -5,6 +5,7 @@
 #ifndef DEVICE_U2F_U2F_APDU_RESPONSE_H_
 #define DEVICE_U2F_U2F_APDU_RESPONSE_H_
 
+#include <memory>
 #include <vector>
 
 #include "base/gtest_prod_util.h"
@@ -15,7 +16,7 @@ namespace device {
 // APDU responses are defined as part of ISO 7816-4. Serialized responses
 // consist of a data field of varying length, up to a maximum 65536, and a
 // two byte status field.
-class U2fApduResponse : public base::RefCountedThreadSafe<U2fApduResponse> {
+class U2fApduResponse {
  public:
   // Status bytes are specified in ISO 7816-4
   enum class Status : uint16_t {
@@ -24,20 +25,19 @@ class U2fApduResponse : public base::RefCountedThreadSafe<U2fApduResponse> {
     SW_WRONG_DATA = 0x6A80,
   };
 
+  U2fApduResponse(std::vector<uint8_t> message, Status response_status);
+  ~U2fApduResponse();
+
   // Create a APDU response from the serialized message
-  static scoped_refptr<U2fApduResponse> CreateFromMessage(
+  static std::unique_ptr<U2fApduResponse> CreateFromMessage(
       const std::vector<uint8_t>& data);
   std::vector<uint8_t> GetEncodedResponse() const;
   const std::vector<uint8_t> data() const { return data_; };
   Status status() const { return response_status_; };
 
  private:
-  friend class base::RefCountedThreadSafe<U2fApduResponse>;
   FRIEND_TEST_ALL_PREFIXES(U2fApduTest, TestDeserializeResponse);
 
-  U2fApduResponse(std::vector<uint8_t> message, Status response_status);
-  ~U2fApduResponse();
-
   Status response_status_;
   std::vector<uint8_t> data_;
 };