Add diagnostic printout to RTC_DCHECK_RUN_ON.

When using a SequenceChecker, this adds a bit more information
about why the check failed.

Example (The "Expects" line is new):

# Fatal error in: foo.cc, line 380
# last system error: 0
# Check failed: (&thread_checker_)->IsCurrent()
# Expects: System queue: 0x7fff69541330, TaskQueue: 0x101804370 (not current), Thread: 0x10053cdc0

Bug: none
Change-Id: I3743e1d80f369f15219de5946e9e081f998b9b17
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/176569
Commit-Queue: Tommi <tommi@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31466}
diff --git a/rtc_base/synchronization/sequence_checker_unittest.cc b/rtc_base/synchronization/sequence_checker_unittest.cc
index a173a82..6fcb522 100644
--- a/rtc_base/synchronization/sequence_checker_unittest.cc
+++ b/rtc_base/synchronization/sequence_checker_unittest.cc
@@ -31,7 +31,7 @@
   int CalledOnSequence() RTC_RUN_ON(sequence_checker_) { return guarded_; }
 
   void CallMeFromSequence() {
-    RTC_DCHECK_RUN_ON(&sequence_checker_) << "Should be called on sequence";
+    RTC_DCHECK_RUN_ON(&sequence_checker_);
     guarded_ = 41;
   }