Rename shell namespace to service_manager

ash/mus/app_launch_unittest.cc

Index: ash/mus/app_launch_unittest.cc
diff --git a/ash/mus/app_launch_unittest.cc b/ash/mus/app_launch_unittest.cc
index fdd5a7d8b2c14c61098ef6ed027b2b323c797f1f..6a23147f61dd021fabd56930b507e512cab3f245 100644
--- a/ash/mus/app_launch_unittest.cc
+++ b/ash/mus/app_launch_unittest.cc
@@ -16,7 +16,7 @@ void RunCallback(bool* success, const base::Closure& callback, bool result) {
   callback.Run();
 }
 
-class AppLaunchTest : public shell::test::ServiceTest {
+class AppLaunchTest : public service_manager::test::ServiceTest {
  public:
   AppLaunchTest() : ServiceTest("exe:mash_unittests") {}
   ~AppLaunchTest() override {}