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

webrtc/base/sigslot_unittest.cc

 /*
  *  Copyright 2012 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 14 matching lines @@
 
 class SigslotDefault : public testing::Test, public sigslot::has_slots<> {
  protected:
   sigslot::signal0<> signal_;
 };
 
 template<class slot_policy = sigslot::single_threaded,
          class signal_policy = sigslot::single_threaded>
 class SigslotReceiver : public sigslot::has_slots<slot_policy> {
  public:
-  SigslotReceiver() : signal_(NULL), signal_count_(0) {
-  }
+  SigslotReceiver() : signal_(nullptr), signal_count_(0) {}
   ~SigslotReceiver() {
   }
 
   void Connect(sigslot::signal0<signal_policy>* signal) {
     if (!signal) return;
     Disconnect();
     signal_ = signal;
     signal->connect(this,
                     &SigslotReceiver<slot_policy, signal_policy>::OnSignal);
   }
   void Disconnect() {
     if (!signal_) return;
     signal_->disconnect(this);
-    signal_ = NULL;
+    signal_ = nullptr;
   }
   void OnSignal() {
     ++signal_count_;
   }
   int signal_count() { return signal_count_; }
 
  private:
   sigslot::signal0<signal_policy>* signal_;
   int signal_count_;
 };
@@ skipping 176 matching lines @@
   sigslot::signal0<>* signal = new sigslot::signal0<>;
   SigslotReceiver<>* receiver = new SigslotReceiver<>();
   receiver->Connect(signal);
   (*signal)();
   EXPECT_EQ(1, receiver->signal_count());
 
   delete receiver;
   (*signal)();
   delete signal;
 }