Revert of base: Remove use of MessageLoopProxy

base/trace_event/trace_event_system_stats_monitor_unittest.cc

Index: base/trace_event/trace_event_system_stats_monitor_unittest.cc
diff --git a/base/trace_event/trace_event_system_stats_monitor_unittest.cc b/base/trace_event/trace_event_system_stats_monitor_unittest.cc
index 03dff591cfa75372263f6b2d0d5c513cb67362a7..995f53bd2d475a54d438068ee1c9ef0485f2a776 100644
--- a/base/trace_event/trace_event_system_stats_monitor_unittest.cc
+++ b/base/trace_event/trace_event_system_stats_monitor_unittest.cc
@@ -7,6 +7,7 @@
 #include <sstream>
 #include <string>
 
+#include "base/message_loop/message_loop.h"
 #include "base/trace_event/trace_event_impl.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -35,7 +36,8 @@
 
   // Creating a system stats monitor adds it to the TraceLog observer list.
   scoped_ptr<TraceEventSystemStatsMonitor> system_stats_monitor(
-      new TraceEventSystemStatsMonitor(message_loop.task_runner()));
+      new TraceEventSystemStatsMonitor(
+          message_loop.message_loop_proxy()));
   EXPECT_EQ(1u, TraceLog::GetInstance()->GetObserverCountForTest());
   EXPECT_TRUE(
       TraceLog::GetInstance()->HasEnabledStateObserver(