Add an idle task to periodically sweep canceled delayed tasks

third_party/WebKit/Source/platform/BUILD.gn

Index: third_party/WebKit/Source/platform/BUILD.gn
diff --git a/third_party/WebKit/Source/platform/BUILD.gn b/third_party/WebKit/Source/platform/BUILD.gn
index b567a2426b674fdf9cf0cf7f0a4024164da05ba4..41a435f88c1fe27b8541b6106490630017878659 100644
--- a/third_party/WebKit/Source/platform/BUILD.gn
+++ b/third_party/WebKit/Source/platform/BUILD.gn
@@ -1208,6 +1208,8 @@ component("platform") {
     "scheduler/base/work_queue_sets.cc",
     "scheduler/base/work_queue_sets.h",
     "scheduler/child/compositor_worker_scheduler.cc",
+    "scheduler/child/idle_canceled_delayed_task_sweeper.cc",
+    "scheduler/child/idle_canceled_delayed_task_sweeper.h",
     "scheduler/child/idle_helper.cc",
     "scheduler/child/idle_helper.h",
     "scheduler/child/scheduler_helper.cc",
@@ -1785,6 +1787,7 @@ test("blink_platform_unittests") {
     "scheduler/base/time_domain_unittest.cc",
     "scheduler/base/work_queue_sets_unittest.cc",
     "scheduler/base/work_queue_unittest.cc",
+    "scheduler/child/idle_canceled_delayed_task_sweeper_unittest.cc",
     "scheduler/child/idle_helper_unittest.cc",
     "scheduler/child/scheduler_helper_unittest.cc",
     "scheduler/child/scheduler_tqm_delegate_impl_unittest.cc",