Replace NULL with nullptr in all C++ files.

webrtc/pc/quicdatachannel_unittest.cc

 /*
  *  Copyright 2016 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 585 matching lines @@
   ASSERT_FALSE(peer1_.quic_transport_channel()->writable());
   EXPECT_EQ(webrtc::DataChannelInterface::kOpen, data_channel->state());
   EXPECT_EQ(0, observer.on_state_change_count());
   // unwritable => writable
   peer1_.ice_transport_channel()->SetWritable(true);
   ASSERT_TRUE(peer1_.quic_transport_channel()->writable());
   EXPECT_EQ(webrtc::DataChannelInterface::kOpen, data_channel->state());
   EXPECT_EQ(0, observer.on_state_change_count());
 }
 
-// Tests that SetTransportChannel returns false when setting a NULL transport
+// Tests that SetTransportChannel returns false when setting a null transport
 // channel or a transport channel that is not equivalent to the one already set.
 TEST_F(QuicDataChannelTest, SetTransportChannelReturnValue) {
   rtc::scoped_refptr<QuicDataChannel> data_channel =
       peer1_.CreateDataChannelWithTransportChannel(4, "label", "protocol");
   EXPECT_FALSE(data_channel->SetTransportChannel(nullptr));
   QuicTransportChannel* transport_channel = peer1_.quic_transport_channel();
   EXPECT_TRUE(data_channel->SetTransportChannel(transport_channel));
   EXPECT_TRUE(data_channel->SetTransportChannel(transport_channel));
   QuicTransportChannel* other_transport_channel =
       peer2_.quic_transport_channel();
@@ skipping 32 matching lines @@
   size_t bytes_read2;
   ASSERT_TRUE(webrtc::ParseQuicDataMessageHeader(
       header2.data<char>(), header2.size(), &decoded_data_channel_id2,
       &decoded_message_id2, &bytes_read2));
   EXPECT_EQ(data_channel_id2, decoded_data_channel_id2);
   EXPECT_EQ(message_id2, decoded_message_id2);
   EXPECT_EQ(8u, bytes_read2);
 }
 
 }  // namespace