mus: Makes ~WindowTreeClient reset context factory

ui/aura/mus/window_tree_client.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/aura/mus/window_tree_client.h"
 
 #include <stddef.h>
 
 #include <string>
 #include <utility>
@@ skipping 171 matching lines @@
   // Allow for a null request in tests.
   if (request.is_pending())
     binding_.Bind(std::move(request));
   client::GetTransientWindowClient()->AddObserver(this);
   if (window_manager_delegate)
     window_manager_delegate->SetWindowManagerClient(this);
   if (connector) {  // |connector| can be null in tests.
     gpu_ = ui::Gpu::Create(connector, std::move(io_task_runner));
     compositor_context_factory_ =
         base::MakeUnique<MusContextFactory>(gpu_.get());
+    initial_context_factory_ = Env::GetInstance()->context_factory();
     Env::GetInstance()->set_context_factory(compositor_context_factory_.get());
   }
 }
 
 WindowTreeClient::~WindowTreeClient() {
   in_destructor_ = true;
 
   for (WindowTreeClientObserver& observer : observers_)
     observer.OnWillDestroyClient(this);
 
   // Clients should properly delete all of their windows before shutdown.
   CHECK(windows_.empty());
 
   capture_synchronizer_.reset();
 
   client::GetTransientWindowClient()->RemoveObserver(this);
+
+  Env* env = Env::GetInstance();
+  if (compositor_context_factory_ &&
+      env->context_factory() == compositor_context_factory_.get()) {
+    env->set_context_factory(initial_context_factory_);
+  }
 }
 
 void WindowTreeClient::ConnectViaWindowTreeFactory() {
   // The client id doesn't really matter, we use 101 purely for debugging.
   client_id_ = 101;
 
   ui::mojom::WindowTreeFactoryPtr factory;
   connector_->BindInterface(ui::mojom::kServiceName, &factory);
   ui::mojom::WindowTreePtr window_tree;
   factory->CreateWindowTree(MakeRequest(&window_tree),
@@ skipping 1603 matching lines @@
   return ScheduleInFlightChange(base::MakeUnique<InFlightCaptureChange>(
       this, capture_synchronizer_.get(), window));
 }
 
 uint32_t WindowTreeClient::CreateChangeIdForFocus(WindowMus* window) {
   return ScheduleInFlightChange(base::MakeUnique<InFlightFocusChange>(
       this, focus_synchronizer_.get(), window));
 }
 
 }  // namespace aura