Added notification when user presses backspace to use new shortcut.

chrome/browser/ui/views/frame/browser_view.h

Index: chrome/browser/ui/views/frame/browser_view.h
diff --git a/chrome/browser/ui/views/frame/browser_view.h b/chrome/browser/ui/views/frame/browser_view.h
index be01656f904ad23f2e6a3dff565dcf40cf3c34c9..4a2d1eccdc97193be9ea3e7c4f4256cf90f0f19d 100644
--- a/chrome/browser/ui/views/frame/browser_view.h
+++ b/chrome/browser/ui/views/frame/browser_view.h
@@ -24,6 +24,7 @@
 #include "chrome/browser/ui/infobar_container_delegate.h"
 #include "chrome/browser/ui/signin_view_controller.h"
 #include "chrome/browser/ui/tabs/tab_strip_model_observer.h"
+#include "chrome/browser/ui/views/backspace_new_shortcut_bubble.h"
 #include "chrome/browser/ui/views/exclusive_access_bubble_views_context.h"
 #include "chrome/browser/ui/views/extensions/extension_keybinding_registry_views.h"
 #include "chrome/browser/ui/views/frame/browser_frame.h"
@@ -289,6 +290,7 @@ class BrowserView : public BrowserWindow,
   bool ShouldHideUIForFullscreen() const override;
   bool IsFullscreen() const override;
   bool IsFullscreenBubbleVisible() const override;
+  void ShowBackspaceNewShortcutBubble(bool forward) override;
   LocationBar* GetLocationBar() const override;
   void SetFocusToLocationBar(bool select_all) override;
   void UpdateReloadStopState(bool is_loading, bool force) override;
@@ -668,6 +670,8 @@ class BrowserView : public BrowserWindow,
 
   std::unique_ptr<ExclusiveAccessBubbleViews> exclusive_access_bubble_;
 
+  std::unique_ptr<BackspaceNewShortcutBubble> backspace_new_shortcut_bubble_;
+
 #if defined(OS_WIN)
   // Helper class to listen for completion of first page load.
   std::unique_ptr<LoadCompleteListener> load_complete_listener_;