services/ui: Have an explicit lifetime/ownership of ui::GpuService.

ui/views/mus/window_manager_connection.cc

Index: ui/views/mus/window_manager_connection.cc
diff --git a/ui/views/mus/window_manager_connection.cc b/ui/views/mus/window_manager_connection.cc
index 2389915defdd9aae355fff84a285c6e9f20683d9..a16ed87092f9cffeb1c1324231104bd4901211ba 100644
--- a/ui/views/mus/window_manager_connection.cc
+++ b/ui/views/mus/window_manager_connection.cc
@@ -41,7 +41,7 @@ WindowManagerConnection::~WindowManagerConnection() {
   // we are still valid.
   client_.reset();
   ui::Clipboard::DestroyClipboardForCurrentThread();
-  ui::GpuService::Terminate();
+  gpu_service_.reset();
   lazy_tls_ptr.Pointer()->Set(nullptr);
 
   if (ViewsDelegate::GetInstance()) {
@@ -150,8 +150,7 @@ WindowManagerConnection::WindowManagerConnection(
     : connector_(connector), identity_(identity) {
   lazy_tls_ptr.Pointer()->Set(this);
 
-  ui::GpuService::Initialize(connector);
-
+  gpu_service_ = ui::GpuService::Initialize(connector);
   client_.reset(new ui::WindowTreeClient(this, nullptr, nullptr));
   client_->ConnectViaWindowTreeFactory(connector_);