Replace NULL with nullptr in all C++ files.

webrtc/modules/audio_processing/aec/system_delay_unittest.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.
  */
 
@@ skipping 33 matching lines @@
   // Dummy input/output speech data.
   static const int kSamplesPerChunk = 160;
   float far_[kSamplesPerChunk];
   float near_[kSamplesPerChunk];
   float out_[kSamplesPerChunk];
   const float* near_ptr_;
   float* out_ptr_;
 };
 
 SystemDelayTest::SystemDelayTest()
-    : handle_(NULL), self_(NULL), samples_per_frame_(0) {
+    : handle_(nullptr), self_(nullptr), samples_per_frame_(0) {
   // Dummy input data are set with more or less arbitrary non-zero values.
   for (int i = 0; i < kSamplesPerChunk; i++) {
     far_[i] = 257.0;
     near_[i] = 514.0;
   }
   memset(out_, 0, sizeof(out_));
   near_ptr_ = near_;
   out_ptr_ = out_;
 }
 
 void SystemDelayTest::SetUp() {
   handle_ = WebRtcAec_Create();
   ASSERT_TRUE(handle_);
   self_ = reinterpret_cast<Aec*>(handle_);
 }
 
 void SystemDelayTest::TearDown() {
   // Free AEC
   WebRtcAec_Free(handle_);
-  handle_ = NULL;
+  handle_ = nullptr;
 }
 
 // In SWB mode nothing is added to the buffer handling with respect to
 // functionality compared to WB. We therefore only verify behavior in NB and WB.
 static const int kSampleRateHz[] = {8000, 16000};
 static const size_t kNumSampleRates =
     sizeof(kSampleRateHz) / sizeof(*kSampleRateHz);
 
 // Default audio device buffer size used.
 static const int kDeviceBufMs = 100;
@@ skipping 505 matching lines @@
         }
         // Verify we are not in a non-causal state.
         EXPECT_FALSE(non_causal);
       }
     }
   }
 }
 
 }  // namespace
 }  // namespace webrtc