allow unit_tests to re-create service manager context.

content/public/test/test_service_manager_context.cc

Index: content/public/test/test_service_manager_context.cc
diff --git a/content/public/test/test_service_manager_context.cc b/content/public/test/test_service_manager_context.cc
index a400534deb04ebf61177ab0d27216b06bfce2f1a..534647db84ac9ea7b36bbb5cd528ee18b0fa7f5d 100644
--- a/content/public/test/test_service_manager_context.cc
+++ b/content/public/test/test_service_manager_context.cc
@@ -4,6 +4,7 @@
 
 #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 {
@@ -11,6 +12,8 @@ namespace content {
 TestServiceManagerContext::TestServiceManagerContext()
     : context_(new ServiceManagerContext) {}
 
-TestServiceManagerContext::~TestServiceManagerContext() {}
+TestServiceManagerContext::~TestServiceManagerContext() {
+  ChildProcessLauncher::ResetRegisteredFilesForTesting();
+}
 
 }  // namespace content