Replace NULL with nullptr in all C++ files.

webrtc/modules/audio_processing/transient/transient_suppression_test.cc

Index: webrtc/modules/audio_processing/transient/transient_suppression_test.cc
diff --git a/webrtc/modules/audio_processing/transient/transient_suppression_test.cc b/webrtc/modules/audio_processing/transient/transient_suppression_test.cc
index 2158a8115893ac4ff621d06309f3562fdc15d694..e36016c93b41d6151ffaf81fa71b1589dd7ef5b1 100644
--- a/webrtc/modules/audio_processing/transient/transient_suppression_test.cc
+++ b/webrtc/modules/audio_processing/transient/transient_suppression_test.cc
@@ -147,16 +147,16 @@ void void_main() {
   // TODO(aluebs): Remove all FileWrappers.
   // Prepare the input file.
   FILE* in_file = fopen(FLAGS_in_file_name.c_str(), "rb");
-  ASSERT_TRUE(in_file != NULL);
+  ASSERT_TRUE(in_file != nullptr);
 
   // Prepare the detection file.
-  FILE* detection_file = NULL;
+  FILE* detection_file = nullptr;
   if (!FLAGS_detection_file_name.empty()) {
     detection_file = fopen(FLAGS_detection_file_name.c_str(), "rb");
   }
 
   // Prepare the reference file.
-  FILE* reference_file = NULL;
+  FILE* reference_file = nullptr;
   if (!FLAGS_reference_file_name.empty()) {
     reference_file = fopen(FLAGS_reference_file_name.c_str(), "rb");
   }
@@ -164,7 +164,7 @@ void void_main() {
   // Prepare the output file.
   std::string out_file_name = test::OutputPath() + "suppressed_keystrokes.pcm";
   FILE* out_file = fopen(out_file_name.c_str(), "wb");
-  ASSERT_TRUE(out_file != NULL);
+  ASSERT_TRUE(out_file != nullptr);
 
   int detection_rate_hz = FLAGS_detection_rate_hz;
   if (detection_rate_hz == 0) {