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

webrtc/base/sigslottester_unittest.cc

 /*
  *  Copyright 2014 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 50 matching lines @@
   EXPECT_EQ(1, slot1.callback_count());
   EXPECT_EQ("hello", capture1);
 }
 
 TEST(SigslotTester, TestSignalWithPointerToConstArgs) {
   sigslot::signal1<const std::string*> source1;
   const std::string* capture1;
   SigslotTester1<const std::string*, const std::string*> slot1(&source1,
                                                                &capture1);
   EXPECT_EQ(0, slot1.callback_count());
-  source1.emit(NULL);
+  source1.emit(nullptr);
   EXPECT_EQ(1, slot1.callback_count());
-  EXPECT_EQ(NULL, capture1);
+  EXPECT_EQ(nullptr, capture1);
 }
 
 TEST(SigslotTester, TestSignalWithConstPointerArgs) {
   sigslot::signal1<std::string* const> source1;
   std::string* capture1;
   SigslotTester1<std::string* const, std::string*> slot1(&source1, &capture1);
   EXPECT_EQ(0, slot1.callback_count());
-  source1.emit(NULL);
+  source1.emit(nullptr);
   EXPECT_EQ(1, slot1.callback_count());
-  EXPECT_EQ(NULL, capture1);
+  EXPECT_EQ(nullptr, capture1);
 }
 
 }  // namespace rtc