[rtp_rtcp] fixed namespaces lint warnings

webrtc/modules/rtp_rtcp/test/testAPI/test_api_audio.cc

 /*
  *  Copyright (c) 2012 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.
  */
 
 #include <algorithm>
 #include <vector>
 #include "testing/gtest/include/gtest/gtest.h"
 
 #include "webrtc/modules/rtp_rtcp/test/testAPI/test_api.h"
 
 #include "webrtc/common_types.h"
 #include "webrtc/modules/rtp_rtcp/include/rtp_rtcp.h"
 #include "webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h"
 #include "webrtc/modules/rtp_rtcp/source/rtp_receiver_audio.h"
 
-using namespace webrtc;
-
+namespace webrtc {
+namespace {
 #define test_rate 64000u
 
 class VerifyingAudioReceiver : public NullRtpData {
  public:
   int32_t OnReceivedPayloadData(
       const uint8_t* payloadData,
       const size_t payloadSize,
       const webrtc::WebRtcRTPHeader* rtpHeader) override {
     if (rtpHeader->header.payloadType == 98 ||
         rtpHeader->header.payloadType == 99) {
@@ skipping 308 matching lines @@
   }
   EXPECT_EQ(0, module1->SendTelephoneEventOutband(32, 9000, 10));
 
   for (;timeStamp <= 740 * 160; timeStamp += 160) {
     EXPECT_EQ(0, module1->SendOutgoingData(webrtc::kAudioFrameSpeech, 96,
                                            timeStamp, -1, test, 4));
     fake_clock.AdvanceTimeMilliseconds(20);
     module1->Process();
   }
 }
+
+}  // namespace
+}  // namespace webrtc