Lazy initialization for ProcessesEventRouter.

chrome/browser/extensions/api/processes/processes_api.h

 // Copyright (c) 2012 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 CHROME_BROWSER_EXTENSIONS_API_PROCESSES_PROCESSES_API_H__
 #define CHROME_BROWSER_EXTENSIONS_API_PROCESSES_PROCESSES_API_H__
 
 #include <set>
 #include <string>
 
+#include "base/memory/scoped_ptr.h"
+#include "chrome/browser/extensions/event_router.h"
 #include "chrome/browser/extensions/extension_function.h"
+#include "chrome/browser/profiles/profile_keyed_service.h"
 #include "chrome/browser/task_manager/task_manager.h"
 #include "content/public/browser/notification_registrar.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/render_widget_host.h"
 
+class Profile;
+
 namespace base {
 class ListValue;
 }
 
 namespace extensions {
 
 // Observes the Task Manager and routes the notifications as events to the
 // extension system.
 class ProcessesEventRouter : public TaskManagerModelObserver,
                              public content::NotificationObserver {
  public:
-  // Single instance of the event router.
-  static ProcessesEventRouter* GetInstance();
-
-  // Safe to call multiple times.
-  void ObserveProfile(Profile* profile);
+  explicit ProcessesEventRouter(Profile* profile);
+  virtual ~ProcessesEventRouter();
 
   // Called when an extension process wants to listen to process events.
   void ListenerAdded();
 
   // Called when an extension process with a listener exits or removes it.
   void ListenerRemoved();
 
   // Called on the first invocation of extension API function. This will call
   // out to the Task Manager to start listening for notifications. Returns
   // true if this was the first call and false if this has already been called.
   void StartTaskManagerListening();
 
   bool is_task_manager_listening() { return task_manager_listening_; }
   int num_listeners() { return listeners_; }
 
  private:
-  friend struct DefaultSingletonTraits<ProcessesEventRouter>;
-
-  ProcessesEventRouter();
-  virtual ~ProcessesEventRouter();
-
   // content::NotificationObserver implementation.
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
   // TaskManagerModelObserver methods.
   virtual void OnItemsAdded(int start, int length) OVERRIDE;
   virtual void OnModelChanged() OVERRIDE {}
   virtual void OnItemsChanged(int start, int length) OVERRIDE;
   virtual void OnItemsRemoved(int start, int length) OVERRIDE {}
   virtual void OnItemsToBeRemoved(int start, int length) OVERRIDE;
 
   // Internal helpers for processing notifications.
   void ProcessHangEvent(content::RenderWidgetHost* widget);
   void ProcessClosedEvent(
       content::RenderProcessHost* rph,
       content::RenderProcessHost::RendererClosedDetails* details);
 
-  void NotifyProfiles(const char* event_name,
-                      scoped_ptr<base::ListValue> event_args);
-
-  void DispatchEvent(Profile* profile,
-                     const char* event_name,
+  void DispatchEvent(const char* event_name,
                      scoped_ptr<base::ListValue> event_args);
 
   // Determines whether there is a registered listener for the specified event.
   // It helps to avoid collecing data if no one is interested in it.
   bool HasEventListeners(const std::string& event_name);
 
   // Used for tracking registrations to process related notifications.
   content::NotificationRegistrar registrar_;
 
-  // Registered profiles.
-  typedef std::set<Profile*> ProfileSet;
-  ProfileSet profiles_;
+  Profile* profile_;
 
   // TaskManager to observe for updates.
   TaskManagerModel* model_;
 
   // Count of listeners, so we avoid sending updates if no one is interested.
   int listeners_;
 
   // Indicator whether we've initialized the Task Manager listeners. This is
   // done once for the lifetime of this object.
   bool task_manager_listening_;
 
   DISALLOW_COPY_AND_ASSIGN(ProcessesEventRouter);
 };
 
+// The profile-keyed service that manages the processes extension API.
+class ProcessesAPI : public ProfileKeyedService,
+                     public EventRouter::Observer {
+ public:
+  explicit ProcessesAPI(Profile* profile);
+  virtual ~ProcessesAPI();
+
+  // Convenience method to get the ProcessesAPI for a profile.
+  static ProcessesAPI* Get(Profile* profile);
+
+  ProcessesEventRouter* processes_event_router() {
+    return processes_event_router_.get();
+  }
+
+  // EventRouter::Observer implementation.
+  virtual void OnListenerAdded(const std::string& event_name) OVERRIDE;
+  virtual void OnListenerRemoved(const std::string& event_name) OVERRIDE;
+
+ private:
+  Profile* profile_;
+
+  // TODO(yoz): Currently, the event router cannot be started lazily
+  // because some API functions use it. It ought to be possible to fix
+  // by moving some state to ProcessesAPI from the event router.

[Matt Perry, 2012/11/09 00:23:34]

Couldn't you have the accessor lazily create the event router?

[Yoyo Zhou, 2012/11/09 00:35:55]

Duh. Thanks.

+  scoped_ptr<extensions::ProcessesEventRouter> processes_event_router_;
+};
 
 // This extension function returns the Process object for the renderer process
 // currently in use by the specified Tab.
 class GetProcessIdForTabFunction : public AsyncExtensionFunction,
                                    public content::NotificationObserver {
  public:
   GetProcessIdForTabFunction();
 
  private:
   virtual ~GetProcessIdForTabFunction() {}
@@ skipping 68 matching lines @@
 #if defined(ENABLE_TASK_MANAGER)
   bool memory_;
 #endif
 
   DECLARE_EXTENSION_FUNCTION_NAME("experimental.processes.getProcessInfo")
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_PROCESSES_PROCESSES_API_H__