Update thread annotiation macros in rtc_base to use RTC_ prefix

BUG=webrtc:8198

Review-Url: https://codereview.webrtc.org/3006133002
Cr-Commit-Position: refs/heads/master@{#19714}
diff --git a/webrtc/rtc_base/swap_queue.h b/webrtc/rtc_base/swap_queue.h
index 3519686..95bae21 100644
--- a/webrtc/rtc_base/swap_queue.h
+++ b/webrtc/rtc_base/swap_queue.h
@@ -192,16 +192,16 @@
 
   // TODO(peah): Change this to use std::function() once we can use C++11 std
   // lib.
-  QueueItemVerifier queue_item_verifier_ GUARDED_BY(crit_queue_);
+  QueueItemVerifier queue_item_verifier_ RTC_GUARDED_BY(crit_queue_);
 
   // (next_read_index_ + num_elements_) % queue_.size() =
   //  next_write_index_
-  size_t next_write_index_ GUARDED_BY(crit_queue_) = 0;
-  size_t next_read_index_ GUARDED_BY(crit_queue_) = 0;
-  size_t num_elements_ GUARDED_BY(crit_queue_) = 0;
+  size_t next_write_index_ RTC_GUARDED_BY(crit_queue_) = 0;
+  size_t next_read_index_ RTC_GUARDED_BY(crit_queue_) = 0;
+  size_t num_elements_ RTC_GUARDED_BY(crit_queue_) = 0;
 
   // queue_.size() is constant.
-  std::vector<T> queue_ GUARDED_BY(crit_queue_);
+  std::vector<T> queue_ RTC_GUARDED_BY(crit_queue_);
 
   RTC_DISALLOW_COPY_AND_ASSIGN(SwapQueue);
 };