Replace NULL with nullptr in all C++ files.

webrtc/modules/audio_coding/neteq/test/neteq_isac_quality_test.cc

 /*
  *  Copyright (c) 2014 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.
  */
 
@@ skipping 36 matching lines @@
  private:
   ISACFIX_MainStruct* isac_encoder_;
   int bit_rate_kbps_;
 };
 
 NetEqIsacQualityTest::NetEqIsacQualityTest()
     : NetEqQualityTest(kIsacBlockDurationMs,
                        kIsacInputSamplingKhz,
                        kIsacOutputSamplingKhz,
                        NetEqDecoder::kDecoderISAC),
-      isac_encoder_(NULL),
+      isac_encoder_(nullptr),
       bit_rate_kbps_(FLAGS_bit_rate_kbps) {}
 
 void NetEqIsacQualityTest::SetUp() {
   ASSERT_EQ(1u, channels_) << "iSAC supports only mono audio.";
   // Create encoder memory.
   WebRtcIsacfix_Create(&isac_encoder_);
-  ASSERT_TRUE(isac_encoder_ != NULL);
+  ASSERT_TRUE(isac_encoder_ != nullptr);
   EXPECT_EQ(0, WebRtcIsacfix_EncoderInit(isac_encoder_, 1));
   // Set bitrate and block length.
   EXPECT_EQ(0, WebRtcIsacfix_Control(isac_encoder_, bit_rate_kbps_ * 1000,
                                      kIsacBlockDurationMs));
   NetEqQualityTest::SetUp();
 }
 
 void NetEqIsacQualityTest::TearDown() {
   // Free memory.
   EXPECT_EQ(0, WebRtcIsacfix_Free(isac_encoder_));
@@ skipping 22 matching lines @@
   EXPECT_GT(value, 0);
   return value;
 }
 
 TEST_F(NetEqIsacQualityTest, Test) {
   Simulate();
 }
 
 }  // namespace test
 }  // namespace webrtc