MD History: Update sign in state in data source

chrome/browser/ui/webui/md_history_ui.h

Index: chrome/browser/ui/webui/md_history_ui.h
diff --git a/chrome/browser/ui/webui/md_history_ui.h b/chrome/browser/ui/webui/md_history_ui.h
index 024a91d0379b93683d0a88f10811220b2d1a6145..7330b19a9084737b6ed310a1f0c96d7641cfa76f 100644
--- a/chrome/browser/ui/webui/md_history_ui.h
+++ b/chrome/browser/ui/webui/md_history_ui.h
@@ -7,6 +7,7 @@
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
+#include "base/memory/weak_ptr.h"
 #include "content/public/browser/web_ui_controller.h"
 #include "ui/base/layout.h"
 
@@ -48,8 +49,14 @@ class MdHistoryUI : public content::WebUIController {
   // Handler for the "menuPromoShown" message from the page. No arguments.
   void HandleMenuPromoShown(const base::ListValue* args);
 
+  // Callback method to update sign in state in data source when profile info
+  // changed.
+  void SignInChanged(bool signed_in);
+
   content::WebUIDataSource* data_source_;  // weak
 
+  base::WeakPtrFactory<MdHistoryUI> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(MdHistoryUI);
 };