More graceful shutdown for ArcSession.

components/arc/arc_session.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_ARC_ARC_SESSION_H_
 #define COMPONENTS_ARC_ARC_SESSION_H_
 
 #include <memory>
 
 #include "base/macros.h"
+#include "base/memory/ref_counted.h"
 #include "base/observer_list.h"
 #include "base/sequenced_task_runner.h"
 #include "base/single_thread_task_runner.h"
+#include "base/task_runner.h"
 #include "components/arc/arc_bridge_service.h"
 
 namespace arc {
 
 // Starts the ARC instance and bootstraps the bridge connection.
 // Clients should implement the Delegate to be notified upon communications
 // being available.
 // The instance can be safely removed 1) before Start() is called, or 2) after
 // OnStopped() is called.
 // The number of instances must be at most one. Otherwise, ARC instances will
@@ skipping 10 matching lines @@
 
     // Called when ARC instance is stopped. This is called exactly once
     // per instance which is Start()ed.
     virtual void OnStopped(ArcBridgeService::StopReason reason) = 0;
 
    private:
     DISALLOW_COPY_AND_ASSIGN(Observer);
   };
 
   // Creates a default instance of ArcSession.
-  static std::unique_ptr<ArcSession> Create();
+  static std::unique_ptr<ArcSession> Create(
+      const scoped_refptr<base::TaskRunner>& blocking_task_runner);
   virtual ~ArcSession();
 
   // Starts and bootstraps a connection with the instance. The Observer's
   // OnReady() will be called if the bootstrapping is successful, or
   // OnStopped() if it is not. Start() should not be called twice or more.
   virtual void Start() = 0;
 
   // Requests to stop the currently-running instance.
   // The completion is notified via OnStopped() of the Delegate.
   virtual void Stop() = 0;
 
+  // Called when Chrome is in shutdown state. This is called when the message
+  // loop is already stopped, and the instance will soon be deleted.
+  virtual void OnShutdown() = 0;
+
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
 
  protected:
   ArcSession();
 
   base::ObserverList<Observer> observer_list_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ArcSession);
 };
 
 }  // namespace arc
 
 #endif  // COMPONENTS_ARC_ARC_SESSION_H_