mojo: kill app_thread before unloading main app library and add tests

mojo/shell/context.cc

Index: mojo/shell/context.cc
diff --git a/mojo/shell/context.cc b/mojo/shell/context.cc
index b4fe8297671d20e368151946a887f2aa4735f02d..3c5ee88fd04fea204ff3aab4e4999cb9b73ea41e 100644
--- a/mojo/shell/context.cc
+++ b/mojo/shell/context.cc
@@ -130,7 +130,7 @@ Context::Context()
   }
 }
 
-Context::~Context() {
+void Context::Shutdown() {
   // mojo_view_manager uses native_viewport. Destroy mojo_view_manager first so
   // that there aren't shutdown ordering issues. Once native viewport service is
   // moved into its own process this can likely be nuked.
@@ -139,7 +139,14 @@ Context::~Context() {
       scoped_ptr<ServiceLoader>(),
       GURL("mojo:mojo_view_manager"));
 #endif
+  service_manager_.SetLoaderForURL(scoped_ptr<ServiceLoader>(),
+                                   GURL("mojo:profile_service"));
   service_manager_.set_default_loader(scoped_ptr<ServiceLoader>());
+  service_manager_.TerminateShellConnections();
+}
+
+Context::~Context() {
+  Shutdown();
 }
 
 }  // namespace shell