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

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

Index: chrome/browser/ui/views/frame/browser_view.cc
diff --git a/chrome/browser/ui/views/frame/browser_view.cc b/chrome/browser/ui/views/frame/browser_view.cc
index d31ac99ae903b9296a4609cd19f2951544232288..96bcae2b41174f5cb9989038a3552685fb10d5da 100644
--- a/chrome/browser/ui/views/frame/browser_view.cc
+++ b/chrome/browser/ui/views/frame/browser_view.cc
@@ -941,7 +941,7 @@ bool BrowserView::IsFullscreenBubbleVisible() const {
   return exclusive_access_bubble_ != nullptr;
 }
 
-void BrowserView::MaybeShowNewBackShortcutBubble(bool forward) {
+void BrowserView::MaybeShowNewBackShortcutBubble(int command_id) {
   if (!new_back_shortcut_bubble_ || !new_back_shortcut_bubble_->IsVisible()) {
     // Show the bubble at most five times.
     PrefService* prefs = browser_->profile()->GetPrefs();
@@ -968,7 +968,7 @@ void BrowserView::MaybeShowNewBackShortcutBubble(bool forward) {
     last_back_shortcut_press_time_ = base::TimeTicks();
   }
 
-  new_back_shortcut_bubble_->UpdateContent(forward);
+  new_back_shortcut_bubble_->UpdateContent(command_id);
 }
 
 void BrowserView::HideNewBackShortcutBubble() {