Replace NULL with nullptr or null in webrtc/base/.

webrtc/base/win32filesystem.h

 /*
  *  Copyright 2004 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.
  */
 
 #ifndef _WEBRTC_BASE_WIN32FILESYSTEM_H__
 #define _WEBRTC_BASE_WIN32FILESYSTEM_H__
 
 #include "fileutils.h"
 
 namespace rtc {
 
 class Win32Filesystem : public FilesystemInterface {
  public:
-  // Opens a file. Returns an open StreamInterface if function succeeds. Otherwise,
-  // returns NULL.
+  // Opens a file. Returns an open StreamInterface if function succeeds.
+  // Otherwise, returns null.
   virtual FileStream *OpenFile(const Pathname &filename, 
                                const std::string &mode);
 
   // This will attempt to delete the path located at filename.
   // If the path points to a folder, it will fail with VERIFY
   virtual bool DeleteFile(const Pathname &filename);
 
   // This will attempt to delete an empty folder. If the path does not point to
   // a folder, it fails with VERIFY. If the folder is not empty, it fails normally
   virtual bool DeleteEmptyFolder(const Pathname &folder);
@@ skipping 22 matching lines @@
   // Returns true if pathname refers to no filesystem object, every parent
   // directory either exists, or is also absent.
   virtual bool IsAbsent(const Pathname& pathname);
 
   // Returns true if pathname represents a temporary location on the system.
   virtual bool IsTemporaryPath(const Pathname& pathname);
 
   // All of the following functions set pathname and return true if successful.
   // Returned paths always include a trailing backslash.
   // If create is true, the path will be recursively created.
-  // If append is non-NULL, it will be appended (and possibly created).
+  // If append is non-null, it will be appended (and possibly created).
 
   virtual std::string TempFilename(const Pathname &dir, const std::string &prefix);
 
   virtual bool GetFileSize(const Pathname& path, size_t* size);
   virtual bool GetFileTime(const Pathname& path, FileTimeType which,
                            time_t* time);
 
   // A folder appropriate for storing temporary files (Contents are
   // automatically deleted when the program exists)
   virtual bool GetTemporaryFolder(Pathname &path, bool create,
                                  const std::string *append);
 
   // Get a temporary folder that is unique to the current user and application.
   virtual bool GetAppTempFolder(Pathname* path);
 
  private:
   // Returns the path to the running application.
   bool GetAppPathname(Pathname* path);
 };
 
 }  // namespace rtc
 
 #endif  // WEBRTC_WINFILESYSTEM_H__