Revert of base: Remove use of MessageLoopProxy

base/files/file_proxy_unittest.cc

Index: base/files/file_proxy_unittest.cc
diff --git a/base/files/file_proxy_unittest.cc b/base/files/file_proxy_unittest.cc
index df0bbc869c2d9a31a0113cf18d9b0961b8f35bae..dbf147645a2e95efa9f38c1731ec039c28fc7a9e 100644
--- a/base/files/file_proxy_unittest.cc
+++ b/base/files/file_proxy_unittest.cc
@@ -9,6 +9,7 @@
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/memory/weak_ptr.h"
+#include "base/message_loop/message_loop.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_restrictions.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -78,7 +79,7 @@
   }
 
   TaskRunner* file_task_runner() const {
-    return file_thread_.task_runner().get();
+    return file_thread_.message_loop_proxy().get();
   }
   const FilePath& test_dir_path() const { return dir_.path(); }
   const FilePath test_path() const { return dir_.path().AppendASCII("test"); }