Implement an initial extension settings API.

chrome/browser/profiles/profile_impl.h

Index: chrome/browser/profiles/profile_impl.h
diff --git a/chrome/browser/profiles/profile_impl.h b/chrome/browser/profiles/profile_impl.h
index 3f1b0a885c000e732ff74b637dc2aa8dde363d77..48e9b841f38eb68a7ecc50b079a407d18bed9ab4 100644
--- a/chrome/browser/profiles/profile_impl.h
+++ b/chrome/browser/profiles/profile_impl.h
@@ -22,6 +22,7 @@
 class ChromeDownloadManagerDelegate;
 class ExtensionPrefs;
 class ExtensionPrefValueMap;
+class ExtensionSettings;
 class PrefService;
 class SpellCheckHostMetrics;
 
@@ -196,6 +197,7 @@ class ProfileImpl : public Profile,
   // 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_refptr<ExtensionSettings> extension_settings_;
   scoped_ptr<ExtensionService> extension_service_;
   scoped_refptr<UserScriptMaster> user_script_master_;
   scoped_refptr<ExtensionDevToolsManager> extension_devtools_manager_;