Replace NULL with nullptr in all C++ files.

webrtc/test/testsupport/frame_reader.cc

Index: webrtc/test/testsupport/frame_reader.cc
diff --git a/webrtc/test/testsupport/frame_reader.cc b/webrtc/test/testsupport/frame_reader.cc
index 2593afd8c8cb002137fe4216f36d777a5fe19a5d..6f9042a465f3f9427d0ad429af94c837b0c1a456 100644
--- a/webrtc/test/testsupport/frame_reader.cc
+++ b/webrtc/test/testsupport/frame_reader.cc
@@ -20,11 +20,12 @@ namespace webrtc {
 namespace test {
 
 FrameReaderImpl::FrameReaderImpl(std::string input_filename,
-                                 int width, int height)
+                                 int width,
+                                 int height)
     : input_filename_(input_filename),
-      width_(width), height_(height),
-      input_file_(NULL) {
-}
+      width_(width),
+      height_(height),
+      input_file_(nullptr) {}
 
 FrameReaderImpl::~FrameReaderImpl() {
   Close();
@@ -40,7 +41,7 @@ bool FrameReaderImpl::Init() {
       width_ * height_ + 2 * ((width_ + 1) / 2) * ((height_ + 1) / 2);
 
   input_file_ = fopen(input_filename_.c_str(), "rb");
-  if (input_file_ == NULL) {
+  if (input_file_ == nullptr) {
     fprintf(stderr, "Couldn't open input file for reading: %s\n",
             input_filename_.c_str());
     return false;
@@ -57,15 +58,15 @@ bool FrameReaderImpl::Init() {
 }
 
 void FrameReaderImpl::Close() {
-  if (input_file_ != NULL) {
+  if (input_file_ != nullptr) {
     fclose(input_file_);
-    input_file_ = NULL;
+    input_file_ = nullptr;
   }
 }
 
 rtc::scoped_refptr<I420Buffer> FrameReaderImpl::ReadFrame() {
-  if (input_file_ == NULL) {
-    fprintf(stderr, "FrameReader is not initialized (input file is NULL)\n");
+  if (input_file_ == nullptr) {
+    fprintf(stderr, "FrameReader is not initialized (input file is null)\n");
     return nullptr;
   }
   rtc::scoped_refptr<I420Buffer> buffer(