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

webrtc/base/httpbase.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 95 matching lines @@
   void recv(HttpData* data);
   void abort(HttpError err);
 
   HttpMode mode() const { return mode_; }
 
   void set_ignore_data(bool ignore) { ignore_data_ = ignore; }
   bool ignore_data() const { return ignore_data_; }
 
   // Obtaining this stream puts HttpBase into stream mode until the stream
   // is closed.  HttpBase can only expose one open stream interface at a time.
-  // Further calls will return NULL.
+  // Further calls will return null.
   StreamInterface* GetDocumentStream();
 
 protected:
   // Do cleanup when the http stream closes (error may be 0 for a clean
   // shutdown), and return the error code to signal.
   HttpError HandleStreamClose(int error);
 
   // DoReceiveLoop acts as a data pump, pulling data from the http stream,
   // pushing it through the HttpParser, and then populating the HttpData object
   // based on the callbacks from the parser.  One of the most interesting
@@ skipping 51 matching lines @@
 
   bool ignore_data_, chunk_data_;
   HttpData::const_iterator header_;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
 } // namespace rtc
 
 #endif // WEBRTC_BASE_HTTPBASE_H__