Mark template class RefCountedObject as final.

pc/test/mock_datachannel.h

 /*
  *  Copyright 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #ifndef PC_TEST_MOCK_DATACHANNEL_H_
 #define PC_TEST_MOCK_DATACHANNEL_H_
 
 #include "pc/datachannel.h"
 #include "test/gmock.h"
 
 namespace webrtc {
 
-class MockDataChannel : public rtc::RefCountedObject<DataChannel> {
+class MockDataChannel : public DataChannel {
  public:
   MockDataChannel(int id, DataState state)
       : MockDataChannel(id, "MockDataChannel", state, "udp", 0, 0, 0, 0) {
   }
   MockDataChannel(
       int id,
       const std::string& label,
       DataState state,
       const std::string& protocol,
       uint32_t messages_sent,
       uint64_t bytes_sent,
       uint32_t messages_received,
       uint64_t bytes_received)
-      : rtc::RefCountedObject<DataChannel>(
-            nullptr, cricket::DCT_NONE, label) {
+      : DataChannel(nullptr, cricket::DCT_NONE, label) {
     EXPECT_CALL(*this, id()).WillRepeatedly(testing::Return(id));
     EXPECT_CALL(*this, state()).WillRepeatedly(testing::Return(state));
     EXPECT_CALL(*this, protocol()).WillRepeatedly(testing::Return(protocol));
     EXPECT_CALL(*this, messages_sent()).WillRepeatedly(
         testing::Return(messages_sent));
     EXPECT_CALL(*this, bytes_sent()).WillRepeatedly(
         testing::Return(bytes_sent));
     EXPECT_CALL(*this, messages_received()).WillRepeatedly(
         testing::Return(messages_received));
     EXPECT_CALL(*this, bytes_received()).WillRepeatedly(
         testing::Return(bytes_received));
   }
   MOCK_CONST_METHOD0(id, int());
   MOCK_CONST_METHOD0(state, DataState());
   MOCK_CONST_METHOD0(protocol, std::string());
   MOCK_CONST_METHOD0(messages_sent, uint32_t());
   MOCK_CONST_METHOD0(bytes_sent, uint64_t());
   MOCK_CONST_METHOD0(messages_received, uint32_t());
   MOCK_CONST_METHOD0(bytes_received, uint64_t());
 };
 
 }  // namespace webrtc
 
 #endif  // PC_TEST_MOCK_DATACHANNEL_H_