Expand the footer in the material design Clear Browsing Data dialog.

chrome/browser/ui/webui/settings/settings_clear_browsing_data_handler.h

 // Copyright 2015 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_UI_WEBUI_SETTINGS_SETTINGS_CLEAR_BROWSING_DATA_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_SETTINGS_SETTINGS_CLEAR_BROWSING_DATA_HANDLER_H_
 
 #include "base/macros.h"
 #include "base/memory/scoped_vector.h"
 #include "chrome/browser/browsing_data/browsing_data_remover.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/webui/settings/settings_page_ui_handler.h"
+#include "components/browser_sync/browser/profile_sync_service.h"
 #include "components/prefs/pref_member.h"
 
 namespace base {
 class ListValue;
 }
 
 namespace content {
 class WebUI;
 }
 
 namespace settings {
 
 // Chrome browser startup settings handler.
 class ClearBrowsingDataHandler : public SettingsPageUIHandler,
-                                 public BrowsingDataRemover::Observer {
+                                 public BrowsingDataRemover::Observer,
+                                 public sync_driver::SyncServiceObserver {
  public:
   explicit ClearBrowsingDataHandler(content::WebUI* webui);
   ~ClearBrowsingDataHandler() override;
 
-  // OptionsPageUIHandler:
+  // WebUIMessageHandler implementation.
   void RegisterMessages() override;
 
  private:
   // Clears browsing data, called by Javascript.
   void HandleClearBrowsingData(const base::ListValue* value);
 
   // BrowsingDataRemover::Observer implementation.
   // Re-enables clear button once all requested data has been removed.
   void OnBrowsingDataRemoverDone() override;
 
   // Updates UI when the pref to allow clearing history changes.
   virtual void OnBrowsingHistoryPrefChanged();
 
+  // Initializes the footer of the dialog. Called by JavaScript when the DOM
+  // is attached.
+  void InitializeFooter(const base::ListValue* args);
+
+  // Implementation of SyncServiceObserver. Updates the footer of the dialog
+  // when the sync state changes.
+  void OnStateChanged() override;
+
+  // Finds out whether we should show notice about other forms of history stored
+  // in user's account.
+  void RefreshHistoryNotice();
+
+  // Called as an asynchronous response to |RefreshHistoryNotice()|. Shows or
+  // hides the footer about other forms of history stored in user's account.
+  void UpdateHistoryNotice(bool show);
+
+  // ProfileSyncService to observe sync state changes.
+  ProfileSyncService* sync_service_;
+
   // If non-null it means removal is in progress.
   BrowsingDataRemover* remover_;
 
   // The WebUI callback ID of the last performClearBrowserData request. There
   // can only be one such request in-flight.
   std::string webui_callback_id_;
 
   // Keeps track of whether clearing LSO data is supported.
   BooleanPrefMember clear_plugin_lso_data_enabled_;
 
   // Keeps track of whether Pepper Flash is enabled and thus Flapper-specific
   // settings and removal options (e.g. Content Licenses) are available.
   BooleanPrefMember pepper_flash_settings_enabled_;
 
   // Keeps track of whether deleting browsing history and downloads is allowed.
   BooleanPrefMember allow_deleting_browser_history_;
 
+  // Whether the sentence about other forms of history stored in user's account
+  // should be displayed in the footer. This value is retrieved asynchronously,
+  // so we cache it here.
+  bool should_show_history_footer_;
+
+  // A weak pointer factory for asynchronous calls referencing this class.
+  base::WeakPtrFactory<ClearBrowsingDataHandler> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(ClearBrowsingDataHandler);
 };
 
 }  // namespace settings
 
 #endif  // CHROME_BROWSER_UI_WEBUI_SETTINGS_SETTINGS_CLEAR_BROWSING_DATA_HANDLER_H_