Replace base/task/ temporary forward headers with their final locations

Note to QA: This merely changes includes and should not be blamed
for files it touched.

Bug: 1255932
Change-Id: I1ce4e31efd5792ebf2080812e665cae838a54972
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3226943
Reviewed-by: Gabriel Charette <gab@chromium.org>
Owners-Override: Gabriel Charette <gab@chromium.org>
Cr-Commit-Position: refs/heads/main@{#932153}

diff --git a/ipc/ipc_send_fds_test.cc b/ipc/ipc_send_fds_test.cc
index bb27836..7359219 100644
--- a/ipc/ipc_send_fds_test.cc
+++ b/ipc/ipc_send_fds_test.cc

@@ -26,7 +26,7 @@
 #include "base/posix/eintr_wrapper.h"
 #include "base/run_loop.h"
 #include "base/synchronization/waitable_event.h"
-#include "base/task/single_thread_task_runner_forward.h"
+#include "base/task/single_thread_task_runner.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "ipc/ipc_message_attachment_set.h"