arc: Reduce logspam when ARC is not enabled/available

chrome/browser/chromeos/arc/process/arc_process_service.h

Index: chrome/browser/chromeos/arc/process/arc_process_service.h
diff --git a/chrome/browser/chromeos/arc/process/arc_process_service.h b/chrome/browser/chromeos/arc/process/arc_process_service.h
index 0b088cc37c50441a6cf3475681e1abc3b1b1aad5..b88343dc6bc9c9e541aa71efe8c39bb3325a88d0 100644
--- a/chrome/browser/chromeos/arc/process/arc_process_service.h
+++ b/chrome/browser/chromeos/arc/process/arc_process_service.h
@@ -59,9 +59,6 @@ class ArcProcessService
   // Returns nullptr before the global instance is ready.
   static ArcProcessService* Get();
 
-  // InstanceHolder<mojom::ProcessInstance>::Observer overrides.
-  void OnInstanceReady() override;
-
   // Returns true if ARC IPC is ready for process list request,
   // otherwise false.
   bool RequestAppProcessList(RequestProcessListCallback callback);
@@ -103,6 +100,13 @@ class ArcProcessService
 
   scoped_refptr<base::SingleThreadTaskRunner> GetTaskRunner();
 
+  // InstanceHolder<mojom::ProcessInstance>::Observer overrides.
+  void OnInstanceReady() override;
+  void OnInstanceClosed() override;
+
+  // Whether ARC is ready to request its process list.
+  bool instance_ready_ = false;
+
   // There are some expensive tasks such as traverse whole process tree that
   // we can't do it on the UI thread. Thus we need an additional thread to
   // handle