mandoline: write this after lunch.

components/font_service/font_service_app.h

Index: components/font_service/font_service_app.h
diff --git a/components/font_service/font_service_app.h b/components/font_service/font_service_app.h
index 9eda20a6959b63065e70c040a12874ba0f21c8ff..7beb4b5fa16fc082098ff06a88e082614f1a0e9a 100644
--- a/components/font_service/font_service_app.h
+++ b/components/font_service/font_service_app.h
@@ -9,6 +9,7 @@
 #include "mojo/application/public/cpp/application_delegate.h"
 #include "mojo/application/public/cpp/interface_factory.h"
 #include "mojo/common/weak_binding_set.h"
+#include "mojo/services/tracing/public/cpp/tracing_impl.h"
 #include "skia/ext/skia_utils_base.h"
 
 namespace font_service {
@@ -41,6 +42,8 @@ class FontServiceApp : public mojo::ApplicationDelegate,
 
   mojo::WeakBindingSet<FontService> bindings_;
 
+  mojo::TracingImpl tracing_;
+
   // We don't want to leak paths to our callers; we thus enumerate the paths of
   // fonts.
   SkTDArray<SkString*> paths_;