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

webrtc/api/proxy.h

 /*
  *  Copyright 2013 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 110 matching lines @@
 class SynchronousMethodCall
     : public rtc::MessageData,
       public rtc::MessageHandler {
  public:
   explicit SynchronousMethodCall(rtc::MessageHandler* proxy)
       : e_(), proxy_(proxy) {}
   ~SynchronousMethodCall() {}
 
   void Invoke(const rtc::Location& posted_from, rtc::Thread* t) {
     if (t->IsCurrent()) {
-      proxy_->OnMessage(NULL);
+      proxy_->OnMessage(nullptr);
     } else {
       e_.reset(new rtc::Event(false, false));
       t->Post(posted_from, this, 0);
       e_->Wait(rtc::Event::kForever);
     }
   }
 
  private:
-  void OnMessage(rtc::Message*) { proxy_->OnMessage(NULL); e_->Set(); }
+  void OnMessage(rtc::Message*) {
+    proxy_->OnMessage(nullptr);
+    e_->Set();
+  }
   std::unique_ptr<rtc::Event> e_;
   rtc::MessageHandler* proxy_;
 };
 
 }  // namespace internal
 
 template <typename C, typename R>
 class MethodCall0 : public rtc::Message,
                     public rtc::MessageHandler {
  public:
@@ skipping 419 matching lines @@
 #define PROXY_WORKER_CONSTMETHOD3(r, method, t1, t2)                       \
   r method(t1 a1, t2 a2, t3 a3) const override {                           \
     ConstMethodCall3<C, r, t1, t2, t3> call(c_, &C::method, std::move(a1), \
                                             std::move(a2), std::move(a3)); \
     return call.Marshal(RTC_FROM_HERE, worker_thread_);                    \
   }
 
 }  // namespace webrtc
 
 #endif  //  WEBRTC_API_PROXY_H_