Add thread annotation macros with RTC_ prefix.
Update samples unittests to use RTC_ versions.

BUG=webrtc:8198

Review-Url: https://codereview.webrtc.org/3011973002
Cr-Original-Commit-Position: refs/heads/master@{#19708}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 5301e3c3db996feb4fd622d4449f740da1064477
diff --git a/rtc_base/thread_checker_unittest.cc b/rtc_base/thread_checker_unittest.cc
index d8ad830..ba5c695 100644
--- a/rtc_base/thread_checker_unittest.cc
+++ b/rtc_base/thread_checker_unittest.cc
@@ -241,16 +241,16 @@
   }
 
  private:
-  void function() RUN_ON(thread_) {}
-  void fun_acccess_var() RUN_ON(thread_) { var_thread_ = 13; }
+  void function() RTC_RUN_ON(thread_) {}
+  void fun_acccess_var() RTC_RUN_ON(thread_) { var_thread_ = 13; }
 
   rtc::Thread* thread_;
   rtc::ThreadChecker checker_;
   rtc::TaskQueue* queue_;
 
-  int var_thread_ ACCESS_ON(thread_);
-  int var_checker_ GUARDED_BY(checker_);
-  int var_queue_ ACCESS_ON(queue_);
+  int var_thread_ RTC_ACCESS_ON(thread_);
+  int var_checker_ RTC_GUARDED_BY(checker_);
+  int var_queue_ RTC_ACCESS_ON(queue_);
 };
 
 // Just in case we ever get lumped together with other compilation units.