allow unit_tests to re-create service manager context.

content/public/test/test_service_manager_context.cc

 // Copyright 2016 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 "content/public/test/test_service_manager_context.h"
 
+#include "content/browser/child_process_launcher.h"
 #include "content/browser/service_manager/service_manager_context.h"
 
 namespace content {
 
 TestServiceManagerContext::TestServiceManagerContext()
     : context_(new ServiceManagerContext) {}
 
-TestServiceManagerContext::~TestServiceManagerContext() {}
+TestServiceManagerContext::~TestServiceManagerContext() {
+  ChildProcessLauncher::ResetRegisteredFilesForTesting();
+}
 
 }  // namespace content