Move scoped_test_dir.* and test_io_thread.* from edk/test to edk/system/test.

mojo/edk/system/test/scoped_test_dir.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "mojo/edk/test/scoped_test_dir.h"
+#include "mojo/edk/system/test/scoped_test_dir.h"
 
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/logging.h"
 
 namespace mojo {
+namespace system {
 namespace test {
 
 ScopedTestDir::ScopedTestDir() {
   CHECK(temp_dir_.CreateUniqueTempDir());
 }
 
 ScopedTestDir::~ScopedTestDir() {}
 
 util::ScopedFILE ScopedTestDir::CreateFile() {
   base::FilePath unused;
   return util::ScopedFILE(
       base::CreateAndOpenTemporaryFileInDir(temp_dir_.path(), &unused));
 }
 
 }  // namespace test
+}  // namespace system
 }  // namespace mojo