Replace NULL with nullptr in all C++ files.

webrtc/modules/audio_processing/audio_buffer.cc

Index: webrtc/modules/audio_processing/audio_buffer.cc
diff --git a/webrtc/modules/audio_processing/audio_buffer.cc b/webrtc/modules/audio_processing/audio_buffer.cc
index 02b8537c07857cc8085ec6cd1707fc2c69885624..0e28238dde94092c5faa09a9c00a4815fecea2ce 100644
--- a/webrtc/modules/audio_processing/audio_buffer.cc
+++ b/webrtc/modules/audio_processing/audio_buffer.cc
@@ -49,19 +49,19 @@ AudioBuffer::AudioBuffer(size_t input_num_frames,
                          size_t process_num_frames,
                          size_t num_process_channels,
                          size_t output_num_frames)
-  : input_num_frames_(input_num_frames),
-    num_input_channels_(num_input_channels),
-    proc_num_frames_(process_num_frames),
-    num_proc_channels_(num_process_channels),
-    output_num_frames_(output_num_frames),
-    num_channels_(num_process_channels),
-    num_bands_(NumBandsFromSamplesPerChannel(proc_num_frames_)),
-    num_split_frames_(rtc::CheckedDivExact(proc_num_frames_, num_bands_)),
-    mixed_low_pass_valid_(false),
-    reference_copied_(false),
-    activity_(AudioFrame::kVadUnknown),
-    keyboard_data_(NULL),
-    data_(new IFChannelBuffer(proc_num_frames_, num_proc_channels_)) {
+    : input_num_frames_(input_num_frames),
+      num_input_channels_(num_input_channels),
+      proc_num_frames_(process_num_frames),
+      num_proc_channels_(num_process_channels),
+      output_num_frames_(output_num_frames),
+      num_channels_(num_process_channels),
+      num_bands_(NumBandsFromSamplesPerChannel(proc_num_frames_)),
+      num_split_frames_(rtc::CheckedDivExact(proc_num_frames_, num_bands_)),
+      mixed_low_pass_valid_(false),
+      reference_copied_(false),
+      activity_(AudioFrame::kVadUnknown),
+      keyboard_data_(nullptr),
+      data_(new IFChannelBuffer(proc_num_frames_, num_proc_channels_)) {
   RTC_DCHECK_GT(input_num_frames_, 0);
   RTC_DCHECK_GT(proc_num_frames_, 0);
   RTC_DCHECK_GT(output_num_frames_, 0);
@@ -182,7 +182,7 @@ void AudioBuffer::CopyTo(const StreamConfig& stream_config,
 }
 
 void AudioBuffer::InitForNewData() {
-  keyboard_data_ = NULL;
+  keyboard_data_ = nullptr;
   mixed_low_pass_valid_ = false;
   reference_copied_ = false;
   activity_ = AudioFrame::kVadUnknown;
@@ -328,7 +328,7 @@ const int16_t* AudioBuffer::mixed_low_pass_data() {
 
 const int16_t* AudioBuffer::low_pass_reference(int channel) const {
   if (!reference_copied_) {
-    return NULL;
+    return nullptr;
   }
 
   return low_pass_reference_channels_->channels()[channel];