Eliminate mojo::Shell client lib class

ui/views/mus/window_tree_host_mus.cc

Index: ui/views/mus/window_tree_host_mus.cc
diff --git a/ui/views/mus/window_tree_host_mus.cc b/ui/views/mus/window_tree_host_mus.cc
index 6326e859155306fde936cb26d4d9f4a98a590af9..507adc56faa06effb13dffc9946533975e25b7e6 100644
--- a/ui/views/mus/window_tree_host_mus.cc
+++ b/ui/views/mus/window_tree_host_mus.cc
@@ -16,13 +16,13 @@ namespace views {
 ////////////////////////////////////////////////////////////////////////////////
 // WindowTreeHostMus, public:
 
-WindowTreeHostMus::WindowTreeHostMus(mojo::Shell* shell,
+WindowTreeHostMus::WindowTreeHostMus(mojo::Connector* connector,
                                      NativeWidgetMus* native_widget,
                                      mus::Window* window)
     : native_widget_(native_widget),
       show_state_(ui::PLATFORM_WINDOW_STATE_UNKNOWN) {
   SetPlatformWindow(
-      make_scoped_ptr(new PlatformWindowMus(this, shell, window)));
+      make_scoped_ptr(new PlatformWindowMus(this, connector, window)));
   // The location of events is already transformed, and there is no way to
   // correctly determine the reverse transform. So, don't attempt to transform
   // event locations, else the root location is wrong.