Remove unused include (thread_scheduler.h).

Change-Id: I9689fd0a2501e810e0ea1ac91d8042e697b5f422
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2253599
Commit-Queue: Tal Pressman <talp@chromium.org>
Commit-Queue: Kouhei Ueno <kouhei@chromium.org>
Auto-Submit: Tal Pressman <talp@chromium.org>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Cr-Commit-Position: refs/heads/master@{#780200}

third_party/blink/renderer/core/dom/document.cc

@@ -314,7 +314,6 @@
 #include "third_party/blink/renderer/platform/scheduler/public/event_loop.h"
 #include "third_party/blink/renderer/platform/scheduler/public/frame_or_worker_scheduler.h"
 #include "third_party/blink/renderer/platform/scheduler/public/post_cross_thread_task.h"
-#include "third_party/blink/renderer/platform/scheduler/public/thread_scheduler.h"
 #include "third_party/blink/renderer/platform/text/platform_locale.h"
 #include "third_party/blink/renderer/platform/web_test_support.h"
 #include "third_party/blink/renderer/platform/weborigin/origin_access_entry.h"