image_decoder: Delay shutdown on idle

services/image_decoder/image_decoder_service.h

Index: services/image_decoder/image_decoder_service.h
diff --git a/services/image_decoder/image_decoder_service.h b/services/image_decoder/image_decoder_service.h
index 4babc6d1b94602da11e70c575d4dda59ec044116..643a130ced9dffba23b9299e2ec7ac1432ce9c56 100644
--- a/services/image_decoder/image_decoder_service.h
+++ b/services/image_decoder/image_decoder_service.h
@@ -9,6 +9,7 @@
 
 #include "base/callback.h"
 #include "base/macros.h"
+#include "base/memory/weak_ptr.h"
 #include "services/service_manager/public/cpp/service.h"
 #include "services/service_manager/public/cpp/service_context_ref.h"
 
@@ -29,7 +30,11 @@ class ImageDecoderService : public service_manager::Service {
   bool OnStop() override;
 
  private:
+  void MaybeRequestQuitDelayed();
+  void MaybeRequestQuit();
+
   std::unique_ptr<service_manager::ServiceContextRefFactory> ref_factory_;
+  base::WeakPtrFactory<ImageDecoderService> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageDecoderService);
 };