Convert the PluginService interface to be an async wrapper around PluginList.

chrome/browser/extensions/extension_content_settings_api.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_CONTENT_SETTINGS_API_H__
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_CONTENT_SETTINGS_API_H__
 #pragma once
 
 #include "chrome/browser/extensions/extension_function.h"
 
 namespace webkit {
 namespace npapi {
-
-class PluginList;
-
+class PluginGroup;
 }
 }
 
 class ClearContentSettingsFunction : public SyncExtensionFunction {
  public:
   virtual bool RunImpl();
   DECLARE_EXTENSION_FUNCTION_NAME(
       "experimental.contentSettings.clear")
 };
 
@@ skipping 14 matching lines @@
 class GetResourceIdentifiersFunction : public AsyncExtensionFunction {
  public:
   virtual bool RunImpl();
   DECLARE_EXTENSION_FUNCTION_NAME(
       "experimental.contentSettings.getResourceIdentifiers")
 
  private:
   FRIEND_TEST_ALL_PREFIXES(ExtensionApiTest,
                            ContentSettingsGetResourceIdentifiers);
 
-  void GetPluginsOnFileThread();
-
-  // Used to override the global plugin list in tests.
-  static void SetPluginListForTesting(webkit::npapi::PluginList* plugin_list);
+  void OnGotPluginGroups(const std::vector<webkit::npapi::PluginGroup>& groups);
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_CONTENT_SETTINGS_API_H__