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

webrtc/base/fileutils.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.
  */
 
@@ skipping 67 matching lines @@
 
 class FilesystemInterface {
  public:
   virtual ~FilesystemInterface() {}
 
   // Returns a DirectoryIterator for a given pathname.
   // TODO: Do fancy abstracted stuff
   virtual DirectoryIterator* IterateDirectory();
 
   // Opens a file. Returns an open StreamInterface if function succeeds.
-  // Otherwise, returns NULL.
+  // Otherwise, returns null.
   // TODO: Add an error param to indicate failure reason, similar to
   // FileStream::Open
   virtual FileStream *OpenFile(const Pathname &filename,
                                const std::string &mode) = 0;
 
   // This will attempt to delete the path located at filename.
   // It DCHECKs and returns false if the path points to a folder or a
   // non-existent file.
   virtual bool DeleteFile(const Pathname &filename) = 0;
 
@@ skipping 193 matching lines @@
  private:
   static FilesystemInterface* default_filesystem_;
 
   static FilesystemInterface *EnsureDefaultFilesystem();
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(Filesystem);
 };
 
 }  // namespace rtc
 
 #endif  // WEBRTC_BASE_FILEUTILS_H_