Have mash_browser_tests recreate BackgroundServiceManager per test

chrome/test/base/mash_browser_tests_main.cc

Index: chrome/test/base/mash_browser_tests_main.cc
diff --git a/chrome/test/base/mash_browser_tests_main.cc b/chrome/test/base/mash_browser_tests_main.cc
index 7ff38d4fd633e3d6b355ee7db7ec34899f622635..e5e68a0abbee5b951f20074b905287c064264511 100644
--- a/chrome/test/base/mash_browser_tests_main.cc
+++ b/chrome/test/base/mash_browser_tests_main.cc
@@ -153,9 +153,11 @@ class MashTestLauncherDelegate : public ChromeTestLauncherDelegate {
 
 std::unique_ptr<content::ServiceManagerConnection>
     CreateServiceManagerConnection(MashTestLauncherDelegate* delegate) {
+  delegate->GetMojoTestConnectorForSingleProcess()->Init();
   std::unique_ptr<content::ServiceManagerConnection> connection(
       content::ServiceManagerConnection::Create(
-          delegate->GetMojoTestConnectorForSingleProcess()->Init(),
+          delegate->GetMojoTestConnectorForSingleProcess()
+              ->InitBackgroundServiceManager(),
           base::ThreadTaskRunnerHandle::Get()));
   connection->Start();
   connection->GetConnector()->StartService(mash::session::mojom::kServiceName);