Use standardized accelerator-to-shortcut code for new backspace shortcut UI.

chrome/browser/ui/views/frame/browser_view.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_VIEWS_FRAME_BROWSER_VIEW_H_
 #define CHROME_BROWSER_UI_VIEWS_FRAME_BROWSER_VIEW_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 273 matching lines @@
   void EnterFullscreen(const GURL& url,
                        ExclusiveAccessBubbleType bubble_type) override;
   void ExitFullscreen() override;
   void UpdateExclusiveAccessExitBubbleContent(
       const GURL& url,
       ExclusiveAccessBubbleType bubble_type) override;
   void OnExclusiveAccessUserInput() override;
   bool ShouldHideUIForFullscreen() const override;
   bool IsFullscreen() const override;
   bool IsFullscreenBubbleVisible() const override;
-  void MaybeShowNewBackShortcutBubble(bool forward) override;
+  void MaybeShowNewBackShortcutBubble(int command_id) override;
   void HideNewBackShortcutBubble() override;
   LocationBar* GetLocationBar() const override;
   void SetFocusToLocationBar(bool select_all) override;
   void UpdateReloadStopState(bool is_loading, bool force) override;
   void UpdateToolbar(content::WebContents* contents) override;
   void ResetToolbarTabState(content::WebContents* contents) override;
   void FocusToolbar() override;
   ToolbarActionsBar* GetToolbarActionsBar() override;
   void ToolbarSizeChanged(bool is_animating) override;
   void FocusAppMenu() override;
@@ skipping 398 matching lines @@
   // The class that registers for keyboard shortcuts for extension commands.
   std::unique_ptr<ExtensionKeybindingRegistryViews>
       extension_keybinding_registry_;
 
   mutable base::WeakPtrFactory<BrowserView> activate_modal_dialog_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserView);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_FRAME_BROWSER_VIEW_H_