Delete the tracing service

ash/mus/window_manager_application.h

Index: ash/mus/window_manager_application.h
diff --git a/ash/mus/window_manager_application.h b/ash/mus/window_manager_application.h
index 1dc98d8dfc8d5dd927a7ecda1fe062c742a989ea..b8f8cec5a85d4e6f6bf667d439ddf718e4445b67 100644
--- a/ash/mus/window_manager_application.h
+++ b/ash/mus/window_manager_application.h
@@ -18,7 +18,6 @@
 #include "mojo/public/cpp/bindings/binding.h"
 #include "services/service_manager/public/cpp/binder_registry.h"
 #include "services/service_manager/public/cpp/service.h"
-#include "services/tracing/public/cpp/provider.h"
 #include "services/ui/common/types.h"
 
 namespace aura {
@@ -90,8 +89,6 @@ class WindowManagerApplication : public service_manager::Service {
 
   const bool show_primary_host_on_connect_;
 
-  tracing::Provider tracing_;
-
   std::unique_ptr<views::AuraInit> aura_init_;
 
   std::unique_ptr<WindowManager> window_manager_;