Ensure that --disable-extensions disables extension prefs from being enacted

chrome/browser/extensions/extension_prefs.h

 // Copyright (c) 2011 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_PREFS_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_PREFS_H_
 #pragma once
 
 #include <set>
 #include <string>
@@ skipping 49 matching lines @@
     LAUNCH_REGULAR,
     LAUNCH_FULLSCREEN,
     LAUNCH_WINDOW,
 
     // Launch an app in the in the way a click on the NTP would,
     // if no user pref were set.  Update this constant to change
     // the default for the NTP and chrome.management.launchApp().
     LAUNCH_DEFAULT = LAUNCH_REGULAR
   };
 
-  // Does not assume ownership of |prefs| and |incognito_prefs|.
+  // Does not assume ownership of |prefs| and |extension_pref_value_map|.
+  // Note that you must call Init() to finalize construction.
   ExtensionPrefs(PrefService* prefs,
                  const FilePath& root_dir,
                  ExtensionPrefValueMap* extension_pref_value_map);
   virtual ~ExtensionPrefs();
 
+  // If |extensions_disabled| is true, extension controlled preferences and
+  // content settings do not become effective.
+  void Init(bool extensions_disabled);
+
   // Returns a copy of the Extensions prefs.
   // TODO(erikkay) Remove this so that external consumers don't need to be
   // aware of the internal structure of the preferences.
   base::DictionaryValue* CopyCurrentExtensions();
 
   // Returns true if the specified external extension was uninstalled by the
   // user.
   bool IsExternalExtensionUninstalled(const std::string& id) const;
 
   // Checks whether |extension_id| is disabled. If there's no state pref for
@@ skipping 373 matching lines @@
   // Checks if kPrefBlacklist is set to true in the DictionaryValue.
   // Return false if the value is false or kPrefBlacklist does not exist.
   // This is used to decide if an extension is blacklisted.
   static bool IsBlacklistBitSet(base::DictionaryValue* ext);
 
   // Fix missing preference entries in the extensions that are were introduced
   // in a later Chrome version.
   void FixMissingPrefs(const ExtensionIdSet& extension_ids);
 
   // Installs the persistent extension preferences into |prefs_|'s extension
-  // pref store.
-  void InitPrefStore();
+  // pref store. Does nothing if |extensions_disabled| is true.
+  void InitPrefStore(bool extensions_disabled);
 
   // Migrates the permissions data in the pref store.
   void MigratePermissions(const ExtensionIdSet& extension_ids);
 
   // Checks whether there is a state pref for the extension and if so, whether
   // it matches |check_state|.
   bool DoesExtensionHaveState(const std::string& id,
                               Extension::State check_state) const;
 
   // The pref service specific to this set of extension prefs. Owned by profile.
   PrefService* prefs_;
 
   // Base extensions install directory.
   FilePath install_directory_;
 
   // Weak pointer, owned by Profile.
   ExtensionPrefValueMap* extension_pref_value_map_;
 
   scoped_refptr<ExtensionContentSettingsStore> content_settings_store_;
 
   // The URLs of all of the toolstrips.
   URLList shelf_order_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionPrefs);
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_PREFS_H_