Disable ephemeral apps after they stop running

apps/app_lifetime_monitor.h

 // Copyright 2013 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 APPS_APP_LIFETIME_MONITOR_H_
 #define APPS_APP_LIFETIME_MONITOR_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 13 matching lines @@
 
 // Observes startup of apps and their windows and notifies observers of these
 // events.
 class AppLifetimeMonitor : public KeyedService,
                            public content::NotificationObserver,
                            public AppWindowRegistry::Observer {
  public:
   class Observer {
    public:
     // Called when the app starts running.
-    virtual void OnAppStart(Profile* profile, const std::string& app_id) = 0;
+    virtual void OnAppStart(Profile* profile, const std::string& app_id) {}
     // Called when the app becomes active to the user, i.e. it opens a window.
-    virtual void OnAppActivated(Profile* profile,
-                                const std::string& app_id) = 0;
+    virtual void OnAppActivated(Profile* profile, const std::string& app_id) {}
     // Called when the app becomes inactive to the user.
-    virtual void OnAppDeactivated(Profile* profile,
-                                  const std::string& app_id) = 0;
+    virtual void OnAppDeactivated(Profile* profile, const std::string& app_id) {
+    }
     // Called when the app stops running.
-    virtual void OnAppStop(Profile* profile, const std::string& app_id) = 0;
+    virtual void OnAppStop(Profile* profile, const std::string& app_id) {}
     // Called when chrome is about to terminate. This gives observers a chance
     // to do something before the apps shut down. This is a system-wide event
     // so there is no associated profile and app id.
-    virtual void OnChromeTerminating() = 0;
+    virtual void OnChromeTerminating() {}
 
    protected:
     virtual ~Observer() {}
   };
 
   explicit AppLifetimeMonitor(Profile* profile);
   virtual ~AppLifetimeMonitor();
 
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
@@ skipping 23 matching lines @@
   content::NotificationRegistrar registrar_;
   Profile* profile_;
   ObserverList<Observer> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(AppLifetimeMonitor);
 };
 
 }  // namespace apps
 
 #endif  // APPS_APP_LIFETIME_MONITOR_H_