[TaskScheduler] Remove temporary forwarding headers and mass migrate users

When this CL is approved I will rebase it on top of tree and mass
migrate all callers in a new patch set (TBR'ed change).

[email protected] (for mass migration of existing callers)

Bug: 867421
Change-Id: I41092bbc4824964ee047e0bf53e972c8f6e896a4
Reviewed-on: https://chromium-review.googlesource.com/1161116
Commit-Queue: Gabriel Charette <[email protected]>
Reviewed-by: Gabriel Charette <[email protected]>
Reviewed-by: Sami Kyöstilä <[email protected]>
Cr-Commit-Position: refs/heads/master@{#580845}
diff --git a/components/component_updater/component_updater_service_unittest.cc b/components/component_updater/component_updater_service_unittest.cc
index 04795d6..42552e6 100644
--- a/components/component_updater/component_updater_service_unittest.cc
+++ b/components/component_updater/component_updater_service_unittest.cc
@@ -18,7 +18,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/run_loop.h"
 #include "base/stl_util.h"
-#include "base/task/post_task_forward.h"
+#include "base/task/post_task.h"
 #include "base/test/metrics/histogram_tester.h"
 #include "base/test/scoped_task_environment.h"
 #include "base/threading/thread_task_runner_handle.h"