MD History: Add confirmation dialog when deleting items from the toolbar

chrome/browser/ui/webui/history_ui.h

 // Copyright (c) 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_WEBUI_HISTORY_UI_H_
 #define CHROME_BROWSER_UI_WEBUI_HISTORY_UI_H_
 
 #include "base/macros.h"
 #include "content/public/browser/web_ui_controller.h"
 #include "ui/base/layout.h"
 
+class Profile;
+
 namespace base {
 class RefCountedMemory;
 }
 
 class HistoryUI : public content::WebUIController {
  public:
   explicit HistoryUI(content::WebUI* web_ui);
   ~HistoryUI() override;
 
   static base::RefCountedMemory* GetFaviconResourceBytes(
       ui::ScaleFactor scale_factor);
 
+  // Returns a localized string warning about deleting history. Takes into
+  // account whether or not incognito mode is available.
+  static base::string16 GetDeleteWarningString(Profile* profile);
+
  private:
   DISALLOW_COPY_AND_ASSIGN(HistoryUI);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_HISTORY_UI_H_