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

webrtc/base/opensslidentity.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 12 matching lines @@
 
 typedef struct ssl_ctx_st SSL_CTX;
 
 namespace rtc {
 
 // OpenSSLKeyPair encapsulates an OpenSSL EVP_PKEY* keypair object,
 // which is reference counted inside the OpenSSL library.
 class OpenSSLKeyPair {
  public:
   explicit OpenSSLKeyPair(EVP_PKEY* pkey) : pkey_(pkey) {
-    RTC_DCHECK(pkey_ != NULL);
+    RTC_DCHECK(pkey_ != nullptr);
   }
 
   static OpenSSLKeyPair* Generate(const KeyParams& key_params);
   // Constructs a key pair from the private key PEM string. This must not result
   // in missing public key parameters. Returns null on error.
   static OpenSSLKeyPair* FromPrivateKeyPEMString(
       const std::string& pem_string);
 
   virtual ~OpenSSLKeyPair();
 
@@ skipping 94 matching lines @@
   std::unique_ptr<OpenSSLKeyPair> key_pair_;
   std::unique_ptr<OpenSSLCertificate> certificate_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(OpenSSLIdentity);
 };
 
 
 }  // namespace rtc
 
 #endif  // WEBRTC_BASE_OPENSSLIDENTITY_H_