app_shell: Extract extension runtime data from ExtensionService

apps/shell/shell_extension_system.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_SHELL_SHELL_EXTENSION_SYSTEM_H_
 #define APPS_SHELL_SHELL_EXTENSION_SYSTEM_H_
 
 #include "base/compiler_specific.h"
 #include "chrome/browser/extensions/extension_system.h"
 #include "extensions/common/one_shot_event.h"
@@ skipping 23 matching lines @@
   // Loads an unpacked application from a directory and attempts to launch it.
   // Returns true on success.
   bool LoadAndLaunchApp(const base::FilePath& app_dir);
 
   // BrowserContextKeyedService implementation:
   virtual void Shutdown() OVERRIDE;
 
   // ExtensionSystem implementation:
   virtual void InitForRegularProfile(bool extensions_enabled) OVERRIDE;
   virtual ExtensionService* extension_service() OVERRIDE;
+  virtual RuntimeData* runtime_data() OVERRIDE;

[not at google - send to devlin, 2014/01/18 01:09:04]

I'm curious; what is the general rationale for items on ExtensionSystem vs
BrowserContextKeyedServices?

My personal preference is to have dependencies be explicit, but the Chrome
pattern seems to be to pull everything into BCKS - which is fine, but... this
file implies otherwise. At least, it seems arbitrary. Why is ExtensionRegistry a
BCKS while RuntimeData on ExtensionSystem?

[James Cook, 2014/01/18 02:01:18]

I don't think there is a rationale. I like BCKS because it makes the services
feel more independent. In particular, I find it forces the services to be more
relaxed about their creation order -- it's hard for them to get tied into "this
object must be constructed right here, not a line before or a line after".  For
example, ExtensionSystem initialization is a mess.  But Yoyo felt that
RuntimeData was too simple to merit a BCKS and it seemed reasonable to us to
hang it here.

Do you want me to change it to a BCKS?

[not at google - send to devlin, 2014/01/21 18:47:47]

Hanging off ExtensionSystem SGTM.

   virtual ManagementPolicy* management_policy() OVERRIDE;
   virtual UserScriptMaster* user_script_master() OVERRIDE;
   virtual ProcessManager* process_manager() OVERRIDE;
   virtual StateStore* state_store() OVERRIDE;
   virtual StateStore* rules_store() OVERRIDE;
   virtual InfoMap* info_map() OVERRIDE;
   virtual LazyBackgroundTaskQueue* lazy_background_task_queue()
       OVERRIDE;
   virtual EventRouter* event_router() OVERRIDE;
   virtual ExtensionWarningService* warning_service() OVERRIDE;
   virtual Blacklist* blacklist() OVERRIDE;
   virtual ErrorConsole* error_console() OVERRIDE;
   virtual InstallVerifier* install_verifier() OVERRIDE;
   virtual void RegisterExtensionWithRequestContexts(
       const Extension* extension) OVERRIDE;
   virtual void UnregisterExtensionWithRequestContexts(
       const std::string& extension_id,
       const UnloadedExtensionInfo::Reason reason) OVERRIDE;
   virtual const OneShotEvent& ready() const OVERRIDE;
 
  private:
   content::BrowserContext* browser_context_;  // Not owned.
 
   // Data to be accessed on the IO thread. Must outlive process_manager_.
   scoped_refptr<InfoMap> info_map_;
 
+  scoped_ptr<RuntimeData> runtime_data_;
   scoped_ptr<LazyBackgroundTaskQueue> lazy_background_task_queue_;
   scoped_ptr<EventRouter> event_router_;
   scoped_ptr<ProcessManager> process_manager_;
 
   // Signaled when the extension system has completed its startup tasks.
   OneShotEvent ready_;
 
   DISALLOW_COPY_AND_ASSIGN(ShellExtensionSystem);
 };
 
 }  // namespace extensions
 
 #endif  // APPS_SHELL_SHELL_EXTENSION_SYSTEM_H_