Remove MessageLoop references in /services/resource_coordinator/public/cpp/memory_instrumentation

MessageLoop is going away soon.

This CL was uploaded by git cl split.

R=hjd@chromium.org

Bug: 891670
Change-Id: I989334bbb928f8261e42608f1d6cf115db324a48
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1944852
Auto-Submit: Carlos Caballero <carlscab@google.com>
Reviewed-by: Hector Dearman <hjd@chromium.org>
Commit-Queue: Hector Dearman <hjd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720426}

services/resource_coordinator/public/cpp/memory_instrumentation/tracing_integration_unittest.cc

@@ -8,7 +8,6 @@
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/memory/ref_counted_memory.h"
-#include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/test/test_io_thread.h"