Implement the new Sync Confirmation dialog on Linux and Windows.

chrome/browser/ui/cocoa/browser_window_cocoa.h

Index: chrome/browser/ui/cocoa/browser_window_cocoa.h
diff --git a/chrome/browser/ui/cocoa/browser_window_cocoa.h b/chrome/browser/ui/cocoa/browser_window_cocoa.h
index 4d9d9d2472a278d4a5ea227da3ea7d7168f57b34..221f1c673c2c98ee2c8aa5ae0f94b7d8491d334f 100644
--- a/chrome/browser/ui/cocoa/browser_window_cocoa.h
+++ b/chrome/browser/ui/cocoa/browser_window_cocoa.h
@@ -165,6 +165,7 @@ class BrowserWindowCocoa
   void ShowModalSigninWindow(AvatarBubbleMode mode,
                              signin_metrics::AccessPoint access_point) override;
   void CloseModalSigninWindow() override;
+  void ShowModalSyncConfirmationWindow();
   int GetRenderViewHeightInsetWithDetachedBookmarkBar() override;
   void ExecuteExtensionCommand(const extensions::Extension* extension,
                                const extensions::Command& command) override;