Sync Promo: Add a way to collapse the sync promo

chrome/browser/ui/webui/ntp/new_tab_sync_setup_handler.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_UI_WEBUI_NTP_NEW_TAB_SYNC_SETUP_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_NTP_NEW_TAB_SYNC_SETUP_HANDLER_H_
 
+#include "chrome/browser/prefs/pref_member.h"
 #include "chrome/browser/ui/webui/sync_setup_handler.h"
 
 // The handler for Javascript messages related to the sync setup UI in the new
 // tab page.
 class NewTabSyncSetupHandler : public SyncSetupHandler {
+ public:
+  // Checks if the sync promo should be visible.
+  static bool ShouldShowSyncPromo();
+
+  // WebUIMessageHandler implementation.
+  virtual WebUIMessageHandler* Attach(WebUI* web_ui);
+  virtual void RegisterMessages();
+
+  // NotificationObserver implementation.
+  virtual void Observe(int type,
+                       const NotificationSource& source,
+                       const NotificationDetails& details);
+
  protected:
   virtual void ShowSetupUI();
+
+  // Javascript callback handler to initialize the sync promo UI.
+  void HandleInitializeSyncPromo(const ListValue* args);
+
+  // Javascript callback handler to collapse the sync promo.
+  void HandleCollapseSyncPromo(const ListValue* args);
+
+  // Javascript callback handler to expand the sync promo.
+  void HandleExpandSyncPromo(const ListValue* args);
+
+ private:
+  // Sends the sync login name to the page.
+  void UpdateLogin();
+
+  // Preference for the sync login name.
+  StringPrefMember username_pref_;
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_NTP_NEW_TAB_SYNC_SETUP_HANDLER_H_