aura: Some change to how the client-lib is set up.

services/ui/ws/window_server_test_base.cc

Index: services/ui/ws/window_server_test_base.cc
diff --git a/services/ui/ws/window_server_test_base.cc b/services/ui/ws/window_server_test_base.cc
index 3cc467b0d9338bfd1a417513b5e5ab6f01c1c247..b10722dd64b76b7afc634da89215a6f73766d753 100644
--- a/services/ui/ws/window_server_test_base.cc
+++ b/services/ui/ws/window_server_test_base.cc
@@ -13,9 +13,7 @@
 #include "base/threading/thread_task_runner_handle.h"
 #include "services/service_manager/public/cpp/connector.h"
 #include "services/service_manager/public/cpp/interface_registry.h"
-#include "services/ui/public/cpp/gpu/gpu.h"
 #include "ui/aura/env.h"
-#include "ui/aura/mus/mus_context_factory.h"
 #include "ui/aura/mus/window_tree_client.h"
 #include "ui/aura/mus/window_tree_host_mus.h"
 #include "ui/display/display.h"
@@ -93,13 +91,10 @@ void WindowServerTestBase::SetUp() {
   WindowServerServiceTestBase::SetUp();
 
   env_ = aura::Env::CreateInstance(aura::Env::Mode::MUS);
-  gpu_ = ui::Gpu::Create(connector(), nullptr);
-  compositor_context_factory_ =
-      base::MakeUnique<aura::MusContextFactory>(gpu_.get());
-  env_->set_context_factory(compositor_context_factory_.get());
   display::Screen::SetScreenInstance(&screen_);
   std::unique_ptr<aura::WindowTreeClient> window_manager_window_tree_client =
-      base::MakeUnique<aura::WindowTreeClient>(connector(), this, this);
+      base::MakeUnique<aura::WindowTreeClient>(connector(), nullptr, this,
+                                               this);
   window_manager_window_tree_client->ConnectAsWindowManager();
   window_manager_ = window_manager_window_tree_client.get();
   window_tree_clients_.push_back(std::move(window_manager_window_tree_client));
@@ -115,7 +110,6 @@ void WindowServerTestBase::TearDown() {
   window_tree_hosts_.clear();
   window_tree_clients_.clear();
   env_.reset();
-  gpu_.reset();
   display::Screen::SetScreenInstance(nullptr);
 
   WindowServerServiceTestBase::TearDown();
@@ -277,7 +271,7 @@ void WindowServerTestBase::Create(
     const service_manager::Identity& remote_identity,
     mojom::WindowTreeClientRequest request) {
   window_tree_clients_.push_back(base::MakeUnique<aura::WindowTreeClient>(
-      connector(), this, nullptr, std::move(request)));
+      connector(), nullptr, this, nullptr, std::move(request)));
 }
 
 bool WindowServerTestBase::DeleteWindowTreeHost(