rtc::Event::Wait(kForever): Print stack trace when we deadlock

After being stuck "forever" (3 seconds) waiting for an event to
trigger, log the stack trace of the current thread to aid debugging of
the deadlock.

Bug: webrtc:10308
Change-Id: I04852f191027294d7e7a7f5e63de4c6c7fdd6326
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/128342
Commit-Queue: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27263}
diff --git a/rtc_base/BUILD.gn b/rtc_base/BUILD.gn
index 5882ade..35f1f61 100644
--- a/rtc_base/BUILD.gn
+++ b/rtc_base/BUILD.gn
@@ -247,23 +247,25 @@
 }
 
 rtc_source_set("rtc_event") {
-  deps = [
-    ":checks",
-  ]
-
   if (build_with_chromium) {
-    # Dependency on chromium's waitable_event (in //base).
-    deps += [ "//base" ]
     sources = [
       "../../webrtc_overrides/rtc_base/event.cc",
       "../../webrtc_overrides/rtc_base/event.h",
     ]
+    deps = [
+      ":checks",
+      "//base",  # Dependency on chromium's waitable_event.
+    ]
   } else {
-    deps += [ "synchronization:yield_policy" ]
     sources = [
       "event.cc",
       "event.h",
     ]
+    deps = [
+      ":checks",
+      "synchronization:yield_policy",
+      "system:warn_current_thread_is_deadlocked",
+    ]
   }
 }