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

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

Index: chrome/browser/ui/webui/settings/settings_clear_browsing_data_handler.h
diff --git a/chrome/browser/ui/webui/settings/settings_clear_browsing_data_handler.h b/chrome/browser/ui/webui/settings/settings_clear_browsing_data_handler.h
index 905909473dd33d7ec6731efd8435a7661ef27fd2..fa5520c580673682280431dd2569c5fc6da2e958 100644
--- a/chrome/browser/ui/webui/settings/settings_clear_browsing_data_handler.h
+++ b/chrome/browser/ui/webui/settings/settings_clear_browsing_data_handler.h
@@ -10,6 +10,7 @@
 #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 {
@@ -24,12 +25,13 @@ 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:
@@ -43,6 +45,25 @@ class ClearBrowsingDataHandler : public SettingsPageUIHandler,
   // 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_;
 
@@ -60,6 +81,14 @@ class ClearBrowsingDataHandler : public SettingsPageUIHandler,
   // 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);
 };