Implement the new Sync Confirmation dialog on Linux and Windows.

chrome/browser/ui/browser_window.h

 // Copyright 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_UI_BROWSER_WINDOW_H_
 #define CHROME_BROWSER_UI_BROWSER_WINDOW_H_
 
 #include "base/callback_forward.h"
 #include "build/build_config.h"
 #include "chrome/browser/lifetime/browser_close_manager.h"
@@ skipping 378 matching lines @@
   // |access_point| indicates the access point used to open the Gaia sign in
   // page.
   virtual void ShowModalSigninWindow(
       AvatarBubbleMode mode,
       signin_metrics::AccessPoint access_point) = 0;
 
   // Closes the tab-modal signin flow opened with ShowModalSigninWindow, if it's
   // open. Does nothing otherwise.
   virtual void CloseModalSigninWindow() = 0;
 
+  // Shows the tab modal sync confirmation dialog that informs the user about
+  // sync and gives them a chance to abort signin under the tab modal signin
+  // flow.
+  virtual void ShowModalSyncConfirmationWindow() = 0;
+
   // Returns the height inset for RenderView when detached bookmark bar is
   // shown.  Invoked when a new RenderHostView is created for a non-NTP
   // navigation entry and the bookmark bar is detached.
   virtual int GetRenderViewHeightInsetWithDetachedBookmarkBar() = 0;
 
   // Executes |command| registered by |extension|.
   virtual void ExecuteExtensionCommand(const extensions::Extension* extension,
                                        const extensions::Command& command) = 0;
 
   // Returns object implementing ExclusiveAccessContext interface.
   virtual ExclusiveAccessContext* GetExclusiveAccessContext() = 0;
 
  protected:
   friend class BrowserCloseManager;
   friend class BrowserView;
   virtual void DestroyBrowser() = 0;
 };
 
 #endif  // CHROME_BROWSER_UI_BROWSER_WINDOW_H_