Move tracing namespace from base::debug to base::trace_event.

content/renderer/scheduler/task_queue_selector.h

Index: content/renderer/scheduler/task_queue_selector.h
diff --git a/content/renderer/scheduler/task_queue_selector.h b/content/renderer/scheduler/task_queue_selector.h
index fe20847ad63669639c6dc4dae7892bf6eba4abf9..68684888503f26d67cbdd8c7ccbf8c9e45098368 100644
--- a/content/renderer/scheduler/task_queue_selector.h
+++ b/content/renderer/scheduler/task_queue_selector.h
@@ -11,8 +11,15 @@
 
 namespace base {
 class TaskQueue;
-namespace debug {
+namespace trace_event {
 class TracedValue;
+}  // namespace trace_event
+
+// This is added temporarily. Once the renaming of namespace usages
+// accross all folders are done, this will be removed.
+// TODO(ssid): crrev.com/837303004
+namespace debug {
+using ::base::trace_event::TracedValue;
 }  // namespace debug
 }  // namespace base