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

webrtc/base/ssladapter.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 16 matching lines @@
   void set_ignore_bad_cert(bool ignore) { ignore_bad_cert_ = ignore; }
 
   // Do DTLS or TLS (default is TLS, if unspecified)
   virtual void SetMode(SSLMode mode) = 0;
 
   // StartSSL returns 0 if successful.
   // If StartSSL is called while the socket is closed or connecting, the SSL
   // negotiation will begin as soon as the socket connects.
   virtual int StartSSL(const char* hostname, bool restartable) = 0;
 
-  // Create the default SSL adapter for this platform. On failure, returns NULL
+  // Create the default SSL adapter for this platform. On failure, returns null
   // and deletes |socket|. Otherwise, the returned SSLAdapter takes ownership
   // of |socket|.
   static SSLAdapter* Create(AsyncSocket* socket);
 
  private:
   // If true, the server certificate need not match the configured hostname.
   bool ignore_bad_cert_;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
 typedef bool (*VerificationCallback)(void* cert);
 
 // Call this on the main thread, before using SSL.
 // Call CleanupSSLThread when finished with SSL.
-bool InitializeSSL(VerificationCallback callback = NULL);
+bool InitializeSSL(VerificationCallback callback = nullptr);
 
 // Call to initialize additional threads.
 bool InitializeSSLThread();
 
 // Call to cleanup additional threads, and also the main thread.
 bool CleanupSSL();
 
 ///////////////////////////////////////////////////////////////////////////////
 
 }  // namespace rtc
 
 #endif  // WEBRTC_BASE_SSLADAPTER_H_