Replace NULL with nullptr in all C++ files.

webrtc/modules/audio_coding/neteq/timestamp_scaler_unittest.cc

Index: webrtc/modules/audio_coding/neteq/timestamp_scaler_unittest.cc
diff --git a/webrtc/modules/audio_coding/neteq/timestamp_scaler_unittest.cc b/webrtc/modules/audio_coding/neteq/timestamp_scaler_unittest.cc
index 13c45547aeaeef28ed32964453069dd736b67c3c..75b63bdedcc8759af770cc9685a3657e35e2f950 100644
--- a/webrtc/modules/audio_coding/neteq/timestamp_scaler_unittest.cc
+++ b/webrtc/modules/audio_coding/neteq/timestamp_scaler_unittest.cc
@@ -300,13 +300,14 @@ TEST(TimestampScaler, Failures) {
   static const uint8_t kRtpPayloadType = 17;
   MockDecoderDatabase db;
   EXPECT_CALL(db, GetDecoderInfo(kRtpPayloadType))
-      .WillOnce(ReturnNull());  // Return NULL to indicate unknown payload type.
+      .WillOnce(
+          ReturnNull());  // Return nullptr to indicate unknown payload type.
 
   TimestampScaler scaler(db);
   uint32_t timestamp = 4711;  // Some number.
   EXPECT_EQ(timestamp, scaler.ToInternal(timestamp, kRtpPayloadType));
 
-  Packet* packet = NULL;
+  Packet* packet = nullptr;
   scaler.ToInternal(packet);  // Should not crash. That's all we can test.
 
   EXPECT_CALL(db, Die());  // Called when database object is deleted.