Replace NULL with nullptr in all C++ files.

webrtc/modules/audio_processing/aecm/aecm_core_c.cc

Index: webrtc/modules/audio_processing/aecm/aecm_core_c.cc
diff --git a/webrtc/modules/audio_processing/aecm/aecm_core_c.cc b/webrtc/modules/audio_processing/aecm/aecm_core_c.cc
index d868d6a2a50c890165cd0370c26c8cb2894b8fc8..d9fcf098b26668cf8ec7afecb83775b5b261a0da 100644
--- a/webrtc/modules/audio_processing/aecm/aecm_core_c.cc
+++ b/webrtc/modules/audio_processing/aecm/aecm_core_c.cc
@@ -135,8 +135,7 @@ static void InverseFFTAndWindow(AecmCore* aecm,
   memcpy(aecm->dBufNoisy,
          aecm->dBufNoisy + PART_LEN,
          sizeof(int16_t) * PART_LEN);
-  if (nearendClean != NULL)
-  {
+  if (nearendClean != nullptr) {
     memcpy(aecm->dBufClean,
            aecm->dBufClean + PART_LEN,
            sizeof(int16_t) * PART_LEN);
@@ -295,7 +294,7 @@ int WebRtcAecm_ProcessBlock(AecmCore* aecm,
   uint16_t dfaNoisy[PART_LEN1];
   uint16_t dfaClean[PART_LEN1];
   uint16_t* ptrDfaClean = dfaClean;
-  const uint16_t* far_spectrum_ptr = NULL;
+  const uint16_t* far_spectrum_ptr = nullptr;
 
   // 32 byte aligned buffers (with +8 or +16).
   // TODO(kma): define fft with ComplexInt16.
@@ -341,8 +340,7 @@ int WebRtcAecm_ProcessBlock(AecmCore* aecm,
   // Buffer near and far end signals
   memcpy(aecm->xBuf + PART_LEN, farend, sizeof(int16_t) * PART_LEN);
   memcpy(aecm->dBufNoisy + PART_LEN, nearendNoisy, sizeof(int16_t) * PART_LEN);
-  if (nearendClean != NULL)
-  {
+  if (nearendClean != nullptr) {
     memcpy(aecm->dBufClean + PART_LEN,
            nearendClean,
            sizeof(int16_t) * PART_LEN);
@@ -364,9 +362,7 @@ int WebRtcAecm_ProcessBlock(AecmCore* aecm,
   aecm->dfaNoisyQDomainOld = aecm->dfaNoisyQDomain;
   aecm->dfaNoisyQDomain = (int16_t)zerosDBufNoisy;
 
-
-  if (nearendClean == NULL)
-  {
+  if (nearendClean == nullptr) {
     ptrDfaClean = dfaNoisy;
     aecm->dfaCleanQDomainOld = aecm->dfaNoisyQDomainOld;
     aecm->dfaCleanQDomain = aecm->dfaNoisyQDomain;
@@ -416,8 +412,7 @@ int WebRtcAecm_ProcessBlock(AecmCore* aecm,
   // Get aligned far end spectrum
   far_spectrum_ptr = WebRtcAecm_AlignedFarend(aecm, &far_q, delay);
   zerosXBuf = (int16_t) far_q;
-  if (far_spectrum_ptr == NULL)
-  {
+  if (far_spectrum_ptr == nullptr) {
     return -1;
   }