Replacing SequencedTaskChecker with SequenceChecker.

Bug: webrtc:9883
Change-Id: I5e3189da2a46e6f4ed1a3c5a5dfd2f7d75a16b5d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/130961
Commit-Queue: Sebastian Jansson <srte@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27518}
diff --git a/rtc_base/weak_ptr.h b/rtc_base/weak_ptr.h
index 89969d6..80cb7ee 100644
--- a/rtc_base/weak_ptr.h
+++ b/rtc_base/weak_ptr.h
@@ -18,7 +18,7 @@
 #include "api/scoped_refptr.h"
 #include "rtc_base/ref_count.h"
 #include "rtc_base/ref_counted_object.h"
-#include "rtc_base/sequenced_task_checker.h"
+#include "rtc_base/synchronization/sequence_checker.h"
 
 // The implementation is borrowed from chromium except that it does not
 // implement SupportsWeakPtr.
@@ -104,7 +104,7 @@
 
     ~Flag() override;
 
-    SequencedTaskChecker checker_;
+    ::webrtc::SequenceChecker checker_;
     bool is_valid_;
   };