Take extensions out of Profile into a profile-keyed service, ExtensionSystem.

chrome/browser/extensions/extension_system.h

Index: chrome/browser/extensions/extension_system.h
diff --git a/chrome/browser/extensions/extension_system.h b/chrome/browser/extensions/extension_system.h
new file mode 100644
index 0000000000000000000000000000000000000000..66ccd5297c8e2b0decf19fd54a531ef7d45d3c6c
--- /dev/null
+++ b/chrome/browser/extensions/extension_system.h
@@ -0,0 +1,169 @@
+// 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_EXTENSION_SYSTEM_H_
+#define CHROME_BROWSER_EXTENSIONS_EXTENSION_SYSTEM_H_
+#pragma once
+
+#include <string>
+
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "chrome/browser/profiles/profile_keyed_service.h"
+#include "chrome/common/extensions/extension_constants.h"
+
+class Extension;
+class ExtensionDevToolsManager;
+class ExtensionEventRouter;
+class ExtensionInfoMap;
+class ExtensionMessageService;
+class ExtensionNavigationObserver;
+class ExtensionPrefs;
+class ExtensionPrefValueMap;
+class ExtensionProcessManager;
+class ExtensionService;
+class Profile;
+class UserScriptMaster;
+
+// The ExtensionSystem manages the creation and destruction of services
+// related to extensions. Most objects are shared between normal
+// and incognito Profiles, except for the process manager.

[Aaron Boodman, 2012/02/28 00:21:21]

Nit: just say "except for where called out in comments", to make this comment
slightly less brittle.

[Yoyo Zhou, 2012/02/28 22:58:26]

Done.

+// This interface is analogous to ExtensionServiceInterface; it supports

[Aaron Boodman, 2012/02/28 00:21:21]

Again, no need to mention specific class names which might change. The second
part of the comment stands alone.

[Yoyo Zhou, 2012/02/28 22:58:26]

Done.

+// using TestExtensionSystem for TestingProfiles that don't want all of the
+// extensions baggage in their tests.
+class ExtensionSystem : public ProfileKeyedService {
+ public:
+  ExtensionSystem();
+  virtual ~ExtensionSystem();
+
+  // ProfileKeyedService implementation.
+  virtual void Shutdown() OVERRIDE {}
+
+  // Initializes extensions machinery.
+  // Component extensions are always enabled, external and user extensions
+  // are controlled by |extensions_enabled|.
+  virtual void Init(bool extensions_enabled) = 0;
+
+  // The ExtensionService is created at startup.
+  virtual ExtensionService* extension_service() = 0;
+
+  //  The ExtensionDevToolsManager is created at startup.
+  virtual ExtensionDevToolsManager* devtools_manager() = 0;
+
+  // The UserScriptMaster is created at startup.
+  virtual UserScriptMaster* user_script_master() = 0;
+
+  // The ExtensionProcessManager is created at startup.
+  virtual ExtensionProcessManager* process_manager() = 0;
+
+  // Returns the IO-thread-accessible extension data.
+  virtual ExtensionInfoMap* info_map() = 0;
+
+  // The ExtensionMessageService is created at startup.
+  virtual ExtensionMessageService* message_service() = 0;
+
+  // The ExtensionEventRouter is created at startup.
+  virtual ExtensionEventRouter* event_router() = 0;
+
+  // Called by the ExtensionService that lives in this system. Gives the
+  // info map a chance to react to the load event before the EXTENSION_LOADED
+  // notification has fired. The purpose for handling this event first is to
+  // avoid race conditions by making sure URLRequestContexts learn about new
+  // extensions before anything else needs them to know.
+  virtual void RegisterExtensionWithRequestContexts(
+      const Extension* extension) {}
+
+  // Called by the ExtensionService that lives in this system. Lets the
+  // info map clean up its RequestContexts once all the listeners to the
+  // EXTENSION_UNLOADED notification have finished running.
+  virtual void UnregisterExtensionWithRequestContexts(
+      const std::string& extension_id,
+      const extension_misc::UnloadedExtensionReason reason) {}
+};
+
+// The ExtensionSystem for ProfileImpl and OffTheRecordProfileImpl.
+// Implementation details: non-shared services are owned by
+// ExtensionSystemImpl, a ProfileKeyedService with separate incognito
+// instances. A private Delegate class (also a ProfileKeyedService,
+// but with a shared instance for incognito) keeps the common services.
+class ExtensionSystemImpl : public ExtensionSystem {
+ public:
+  explicit ExtensionSystemImpl(Profile* profile);
+  virtual ~ExtensionSystemImpl();
+
+  // ProfileKeyedService implementation.
+  virtual void Shutdown() OVERRIDE;
+
+  virtual void Init(bool extensions_enabled) OVERRIDE;
+
+  virtual ExtensionService* extension_service() OVERRIDE;  // delegated
+  virtual UserScriptMaster* user_script_master() OVERRIDE;  // delegated
+  virtual ExtensionDevToolsManager* devtools_manager() OVERRIDE;
+  virtual ExtensionProcessManager* process_manager() OVERRIDE;
+  virtual ExtensionInfoMap* info_map() OVERRIDE;  // delegated
+  virtual ExtensionMessageService* message_service() OVERRIDE;  // delegated
+  virtual ExtensionEventRouter* event_router() OVERRIDE;  // delegated
+
+  virtual void RegisterExtensionWithRequestContexts(
+      const Extension* extension) OVERRIDE;
+
+  virtual void UnregisterExtensionWithRequestContexts(
+      const std::string& extension_id,
+      const extension_misc::UnloadedExtensionReason reason) OVERRIDE;
+
+ private:
+  friend class ExtensionSystemDelegateFactory;
+
+  // Owns the Extension-related systems that have a single instance
+  // shared between normal and incognito profiles.
+  class Delegate : public ProfileKeyedService {

[Aaron Boodman, 2012/02/28 00:21:21]

Delegate is a kinda funky name for this class, since the term "delegate" already
has a well-known meaning in the Chrome codebase different than how it is used
here.

Maybe call this Shared?

[Yoyo Zhou, 2012/02/28 22:58:26]

Done.

+   public:
+    explicit Delegate(Profile* profile);
+    virtual ~Delegate();
+
+    // ProfileKeyedService implementation.
+    virtual void Shutdown() OVERRIDE;
+
+    // Initialization takes place in phases.
+    virtual void InitPrefs();
+    void InitInfoMap();
+    void Init(bool extensions_enabled);
+
+    ExtensionService* extension_service();
+    UserScriptMaster* user_script_master();
+    ExtensionInfoMap* info_map();
+    ExtensionMessageService* message_service();
+    ExtensionEventRouter* event_router();
+
+   private:
+    Profile* profile_;
+
+    // The services that are shared between normal and incognito profiles.
+
+    // Keep extension_prefs_ on top of extension_service_ because the latter
+    // maintains a pointer to the first and shall be destructed first.
+    scoped_ptr<ExtensionPrefs> extension_prefs_;
+    scoped_ptr<ExtensionService> extension_service_;
+    scoped_refptr<UserScriptMaster> user_script_master_;
+    // extension_info_map_ needs to outlive extension_process_manager_.
+    scoped_refptr<ExtensionInfoMap> extension_info_map_;
+    scoped_refptr<ExtensionMessageService> extension_message_service_;
+    scoped_ptr<ExtensionEventRouter> extension_event_router_;
+    scoped_ptr<ExtensionNavigationObserver> extension_navigation_observer_;
+  };
+
+  Profile* profile_;
+
+  Delegate* delegate_;
+
+  // The services that have their own instances in incognito.
+  scoped_refptr<ExtensionDevToolsManager> extension_devtools_manager_;
+  // |extension_process_manager_| must be destroyed before the Profile's
+  // |io_data_|. While |extension_process_manager_| still lives, we handle
+  // incoming resource requests from extension processes and those require
+  // access to the ResourceContext owned by |io_data_|.
+  scoped_ptr<ExtensionProcessManager> extension_process_manager_;
+};
+
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_SYSTEM_H_