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

chrome/browser/extensions/extension_prefs.h

Index: chrome/browser/extensions/extension_prefs.h
diff --git a/chrome/browser/extensions/extension_prefs.h b/chrome/browser/extensions/extension_prefs.h
index fe759ac693ca49f28ae154ef359b11816b306783..79034556a5c1e8dec1d35e5037da3545afc7d61f 100644
--- a/chrome/browser/extensions/extension_prefs.h
+++ b/chrome/browser/extensions/extension_prefs.h
@@ -67,10 +67,13 @@ class ExtensionPrefs : public ExtensionContentSettingsStore::Observer {
     LAUNCH_DEFAULT = LAUNCH_REGULAR
   };
 
-  // Does not assume ownership of |prefs| and |incognito_prefs|.
+  // Does not assume ownership of |prefs| and |extension_pref_value_map|.
+  // If |extensions_disabled| is true, extension controlled preferences and
+  // content settings do not become not effective.
   ExtensionPrefs(PrefService* prefs,
                  const FilePath& root_dir,
-                 ExtensionPrefValueMap* extension_pref_value_map);
+                 ExtensionPrefValueMap* extension_pref_value_map,
+                 bool extensions_disabled);
   virtual ~ExtensionPrefs();
 
   // Returns a copy of the Extensions prefs.
@@ -466,8 +469,8 @@ class ExtensionPrefs : public ExtensionContentSettingsStore::Observer {
   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);