Replace NULL with nullptr in all C++ files.

webrtc/p2p/base/dtlstransportchannel_unittest.cc

Index: webrtc/p2p/base/dtlstransportchannel_unittest.cc
diff --git a/webrtc/p2p/base/dtlstransportchannel_unittest.cc b/webrtc/p2p/base/dtlstransportchannel_unittest.cc
index 696135c5b0ce495991e87a4450664d3573441d2b..bb5fd4c641b4ea972675839e944e256759587701 100644
--- a/webrtc/p2p/base/dtlstransportchannel_unittest.cc
+++ b/webrtc/p2p/base/dtlstransportchannel_unittest.cc
@@ -51,7 +51,7 @@ cricket::TransportDescription MakeTransportDescription(
     EXPECT_FALSE(digest_algorithm.empty());
     fingerprint.reset(
         rtc::SSLFingerprint::Create(digest_algorithm, cert->identity()));
-    EXPECT_TRUE(fingerprint.get() != NULL);
+    EXPECT_TRUE(fingerprint.get() != nullptr);
     EXPECT_EQ(rtc::DIGEST_SHA_256, digest_algorithm);
   }
   return cricket::TransportDescription(std::vector<std::string>(), kIceUfrag1,
@@ -426,7 +426,7 @@ class DtlsTestClient : public sigslot::has_slots<> {
       if (data[0] == 23) {
         ASSERT_TRUE(VerifyEncryptedPacket(data, size));
       } else if (IsRtpLeadByte(data[0])) {
-        ASSERT_TRUE(VerifyPacket(data, size, NULL));
+        ASSERT_TRUE(VerifyPacket(data, size, nullptr));
       }
     }
   }
@@ -642,8 +642,8 @@ TEST_F(DtlsTransportChannelTest, TestChannelSetupIce) {
   Negotiate();
   cricket::FakeIceTransport* channel1 = client1_.GetFakeIceTransort(0);
   cricket::FakeIceTransport* channel2 = client2_.GetFakeIceTransort(0);
-  ASSERT_TRUE(channel1 != NULL);
-  ASSERT_TRUE(channel2 != NULL);
+  ASSERT_TRUE(channel1 != nullptr);
+  ASSERT_TRUE(channel2 != nullptr);
   EXPECT_EQ(cricket::ICEROLE_CONTROLLING, channel1->GetIceRole());
   EXPECT_EQ(1U, channel1->IceTiebreaker());
   EXPECT_EQ(kIceUfrag1, channel1->ice_ufrag());