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

talk/media/webrtc/webrtcvoiceengine_unittest.cc

Index: talk/media/webrtc/webrtcvoiceengine_unittest.cc
diff --git a/talk/media/webrtc/webrtcvoiceengine_unittest.cc b/talk/media/webrtc/webrtcvoiceengine_unittest.cc
index 27a9c0271ff9a516da1523f971304fa884a0f224..5fcdf5b3d5182bb710ca6facaddfc31c09c8517e 100644
--- a/talk/media/webrtc/webrtcvoiceengine_unittest.cc
+++ b/talk/media/webrtc/webrtcvoiceengine_unittest.cc
@@ -97,7 +97,7 @@ class WebRtcVoiceEngineTestFake : public testing::Test {
    public:
     explicit ChannelErrorListener(cricket::VoiceMediaChannel* channel)
         : ssrc_(0), error_(cricket::VoiceMediaChannel::ERROR_NONE) {
-      DCHECK(channel != NULL);
+      RTC_DCHECK(channel != NULL);
       channel->SignalMediaError.connect(
           this, &ChannelErrorListener::OnVoiceChannelError);
     }