Revert of base: Remove use of MessageLoopProxy

base/chromeos/memory_pressure_monitor_chromeos.cc

Index: base/chromeos/memory_pressure_monitor_chromeos.cc
diff --git a/base/chromeos/memory_pressure_monitor_chromeos.cc b/base/chromeos/memory_pressure_monitor_chromeos.cc
index 78f78ea2fe125624947eaa23d5aacf120a502373..404c515c8040edb399c6b3715c6b8306a8fc47be 100644
--- a/base/chromeos/memory_pressure_monitor_chromeos.cc
+++ b/base/chromeos/memory_pressure_monitor_chromeos.cc
@@ -7,10 +7,10 @@
 #include <fcntl.h>
 #include <sys/select.h>
 
+#include "base/message_loop/message_loop.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/posix/eintr_wrapper.h"
 #include "base/process/process_metrics.h"
-#include "base/thread_task_runner_handle.h"
 #include "base/time/time.h"
 
 namespace base {
@@ -120,9 +120,10 @@
 }
 
 void MemoryPressureMonitorChromeOS::ScheduleEarlyCheck() {
-  ThreadTaskRunnerHandle::Get()->PostTask(
-      FROM_HERE, Bind(&MemoryPressureMonitorChromeOS::CheckMemoryPressure,
-                      weak_ptr_factory_.GetWeakPtr()));
+  MessageLoop::current()->PostTask(
+      FROM_HERE,
+      Bind(&MemoryPressureMonitorChromeOS::CheckMemoryPressure,
+           weak_ptr_factory_.GetWeakPtr()));
 }
 
 MemoryPressureListener::MemoryPressureLevel