Replace NULL with nullptr in all C++ files.

webrtc/test/testsupport/fileutils.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 120 matching lines @@
     return kCannotFindProjectRootDir;
   }
   if (relative_dir_path_set) {
     path = path + kPathDelimiter + relative_dir_path;
   }
   path = path + kPathDelimiter + ".." + kPathDelimiter + "..";
   char canonical_path[FILENAME_MAX];
 #ifdef WIN32
   BOOL succeeded = PathCanonicalizeA(canonical_path, path.c_str());
 #else
-  bool succeeded = realpath(path.c_str(), canonical_path) != NULL;
+  bool succeeded = realpath(path.c_str(), canonical_path) != nullptr;
 #endif
   if (succeeded) {
     path = std::string(canonical_path) + kPathDelimiter;
     return path;
   } else {
     fprintf(stderr, "Cannot find project root directory!\n");
     return kCannotFindProjectRootDir;
   }
 #endif
 }
@@ skipping 115 matching lines @@
   }
 
   // Fall back on name without architecture or platform.
   return resources_path + name + "." + extension;
 #endif  // defined (WEBRTC_IOS)
 }
 
 size_t GetFileSize(const std::string& filename) {
   FILE* f = fopen(filename.c_str(), "rb");
   size_t size = 0;
-  if (f != NULL) {
+  if (f != nullptr) {
     if (fseek(f, 0, SEEK_END) == 0) {
       size = ftell(f);
     }
     fclose(f);
   }
   return size;
 }
 
 }  // namespace test
 }  // namespace webrtc