app_shell: Extract extension runtime data from ExtensionService

apps/shell/shell_extension_system.h

Index: apps/shell/shell_extension_system.h
diff --git a/apps/shell/shell_extension_system.h b/apps/shell/shell_extension_system.h
index a72e089431be3df49de974c026f7e7b29a94d3cd..2ed83e54c550643bbb7d37114acdaba4c727b663 100644
--- a/apps/shell/shell_extension_system.h
+++ b/apps/shell/shell_extension_system.h
@@ -41,6 +41,7 @@ class ShellExtensionSystem : public ExtensionSystem {
   // 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;
@@ -67,6 +68,7 @@ class ShellExtensionSystem : public ExtensionSystem {
   // 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_;