Reduce FakeArcBridgeService usage.

components/arc/test/fake_arc_bridge_service.h

Index: components/arc/test/fake_arc_bridge_service.h
diff --git a/components/arc/test/fake_arc_bridge_service.h b/components/arc/test/fake_arc_bridge_service.h
index c21811297e7cb573af03bc76a35c2ac8e7decfb0..971ccd902eb8590e71ddbfb77b0f08021f75082d 100644
--- a/components/arc/test/fake_arc_bridge_service.h
+++ b/components/arc/test/fake_arc_bridge_service.h
@@ -23,13 +23,10 @@ class FakeArcBridgeService : public ArcBridgeService {
   void RequestStop() override;
   void OnShutdown() override;
 
+ private:
   void SetReady();
-
   void SetStopped();
 
-  bool HasObserver(const Observer* observer);
-
- private:
   DISALLOW_COPY_AND_ASSIGN(FakeArcBridgeService);
 };