Add RTC_ prefix to (D)CHECKs and related macros.

webrtc/video/video_encoder.cc

Index: webrtc/video/video_encoder.cc
diff --git a/webrtc/video/video_encoder.cc b/webrtc/video/video_encoder.cc
index 8847a1072e10be02e2a04ace53a792d9521448ff..305406b6c0fdbe5fc73bba684b4db53013e0a6b9 100644
--- a/webrtc/video/video_encoder.cc
+++ b/webrtc/video/video_encoder.cc
@@ -20,7 +20,7 @@ namespace webrtc {
 VideoEncoder* VideoEncoder::Create(VideoEncoder::EncoderType codec_type) {
   switch (codec_type) {
     case kH264:
-      DCHECK(H264Encoder::IsSupported());
+      RTC_DCHECK(H264Encoder::IsSupported());
       return H264Encoder::Create();
     case kVp8:
       return VP8Encoder::Create();