Replace NULL with nullptr in all C++ files.

webrtc/base/fileutils.cc

Index: webrtc/base/fileutils.cc
diff --git a/webrtc/base/fileutils.cc b/webrtc/base/fileutils.cc
index a88399505469753dd9734a36d09df1d5898cacf7..e7335244e1227bc98e3576da9e8117f4a0d1729e 100644
--- a/webrtc/base/fileutils.cc
+++ b/webrtc/base/fileutils.cc
@@ -40,7 +40,7 @@ DirectoryIterator::DirectoryIterator()
 #ifdef WEBRTC_WIN
     : handle_(INVALID_HANDLE_VALUE) {
 #else
-    : dir_(NULL), dirent_(NULL) {
+    : dir_(nullptr), dirent_(nullptr) {
 #endif
 }
 
@@ -68,13 +68,13 @@ bool DirectoryIterator::Iterate(const Pathname &dir) {
   if (handle_ == INVALID_HANDLE_VALUE)
     return false;
 #else
-  if (dir_ != NULL)
+  if (dir_ != nullptr)
     closedir(dir_);
   dir_ = ::opendir(directory_.c_str());
-  if (dir_ == NULL)
+  if (dir_ == nullptr)
     return false;
   dirent_ = readdir(dir_);
-  if (dirent_ == NULL)
+  if (dirent_ == nullptr)
     return false;
 
   if (::stat(std::string(directory_ + Name()).c_str(), &stat_) != 0)
@@ -90,7 +90,7 @@ bool DirectoryIterator::Next() {
   return ::FindNextFile(handle_, &data_) == TRUE;
 #else
   dirent_ = ::readdir(dir_);
-  if (dirent_ == NULL)
+  if (dirent_ == nullptr)
     return false;
 
   return ::stat(std::string(directory_ + Name()).c_str(), &stat_) == 0;
@@ -116,7 +116,7 @@ std::string DirectoryIterator::Name() const {
 #endif
 }
 
-FilesystemInterface* Filesystem::default_filesystem_ = NULL;
+FilesystemInterface* Filesystem::default_filesystem_ = nullptr;
 
 FilesystemInterface *Filesystem::EnsureDefaultFilesystem() {
   if (!default_filesystem_) {