Introduce dchecked_cast, and start using it

webrtc/modules/audio_coding/neteq/red_payload_splitter.cc

Index: webrtc/modules/audio_coding/neteq/red_payload_splitter.cc
diff --git a/webrtc/modules/audio_coding/neteq/red_payload_splitter.cc b/webrtc/modules/audio_coding/neteq/red_payload_splitter.cc
index 774832c41669795e1c74c66416a266fd4473376e..c14986dc3934824459e01a554412ef4acfdafd18 100644
--- a/webrtc/modules/audio_coding/neteq/red_payload_splitter.cc
+++ b/webrtc/modules/audio_coding/neteq/red_payload_splitter.cc
@@ -110,7 +110,7 @@ bool RedPayloadSplitter::SplitRed(PacketList* packet_list) {
         new_packet.payload_type = new_header.payload_type;
         new_packet.sequence_number = red_packet.sequence_number;
         new_packet.priority.red_level =
-            rtc::checked_cast<int>((new_headers.size() - 1) - i);
+            rtc::dchecked_cast<int>((new_headers.size() - 1) - i);
         new_packet.payload.SetData(payload_ptr, payload_length);
         new_packets.push_front(std::move(new_packet));
         payload_ptr += payload_length;