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

webrtc/base/thread_checker_unittest.cc

Index: webrtc/base/thread_checker_unittest.cc
diff --git a/webrtc/base/thread_checker_unittest.cc b/webrtc/base/thread_checker_unittest.cc
index a193248eb7a8e053131ea5439719cdd6a4bdcfe7..bcffb523ab7bf4fa32b12f6715efb30bcacca85a 100644
--- a/webrtc/base/thread_checker_unittest.cc
+++ b/webrtc/base/thread_checker_unittest.cc
@@ -37,9 +37,7 @@ class ThreadCheckerClass : public ThreadChecker {
   ThreadCheckerClass() {}
 
   // Verifies that it was called on the same thread as the constructor.
-  void DoStuff() {
-    DCHECK(CalledOnValidThread());
-  }
+  void DoStuff() { RTC_DCHECK(CalledOnValidThread()); }
 
   void DetachFromThread() {
     ThreadChecker::DetachFromThread();