Add a group policy controlling which sites can install extensions.

chrome/browser/extensions/extension_prefs.h

 // Copyright (c) 2012 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>
 #include <vector>
 
 #include "base/memory/linked_ptr.h"
 #include "base/time.h"
 #include "base/values.h"
 #include "chrome/browser/extensions/api/content_settings/content_settings_store.h"
 #include "chrome/browser/extensions/extension_menu_manager.h"
 #include "chrome/browser/extensions/extension_prefs_scope.h"
 #include "chrome/browser/extensions/extension_scoped_prefs.h"
 #include "chrome/browser/extensions/management_policy.h"
 #include "chrome/common/extensions/extension.h"
+#include "chrome/common/extensions/url_pattern_set.h"
 #include "chrome/common/string_ordinal.h"
 
 class ExtensionPrefValueMap;
 class ExtensionSorting;
 class PrefService;
 class URLPatternSet;
 
 namespace extensions {
 struct AlarmPref;
 struct ExtensionOmniboxSuggestion;
@@ skipping 393 matching lines @@
   }
 
   // The underlying PrefService.
   PrefService* pref_service() const { return prefs_; }
 
   // The underlying ExtensionSorting.
   ExtensionSorting* extension_sorting() const {
     return extension_sorting_.get();
   }
 
+  // Describes the URLs that are able to install extensions. See
+  // prefs::kExtensionAllowedInstallSites for more information.
+  URLPatternSet GetAllowedInstallSites();
+
  protected:
   // For unit testing. Enables injecting an artificial clock that is used
   // to query the current time, when an extension is installed.
   virtual base::Time GetCurrentTime() const;
 
  private:
   friend class ExtensionPrefsUninstallExtension;  // Unit test.
 
   // extensions::ContentSettingsStore::Observer methods:
   virtual void OnContentSettingChanged(
@@ skipping 107 matching lines @@
   // Contains all the logic for handling the order for various extension
   // properties.
   scoped_ptr<ExtensionSorting> extension_sorting_;
 
   scoped_refptr<extensions::ContentSettingsStore> content_settings_store_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionPrefs);
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_PREFS_H_