Remove the BackspaceGoesBack flag.

chrome/browser/resources/chromeos/keyboard_overlay.js

 // 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.
 
 // <include src="keyboard_overlay_data.js">
 
 var BASE_KEYBOARD = {
   top: 0,
   left: 0,
   width: 1237,
@@ skipping 209 matching lines @@
 
   if (!isDisplayUIScalingEnabled()) {
     // Zoom screen in
     delete shortcutDataCache['+<>CTRL<>SHIFT'];
     // Zoom screen out
     delete shortcutDataCache['-<>CTRL<>SHIFT'];
     // Reset screen zoom
     delete shortcutDataCache['0<>CTRL<>SHIFT'];
   }
 
-  if (!loadTimeData.getBoolean('backspaceGoesBackFeatureEnabled')) {
-    // If the "backspace key goes back" experiment is not enabled, then we
-    // clear the shortcuts for Backspace and Shift+Backspace to go back or
-    // forward respectively.
-    delete shortcutDataCache['backspace'];
-    delete shortcutDataCache['backspace<>SHIFT'];
-  }
-
   return shortcutDataCache;
 }
 
 /**
  * Returns the keyboard overlay ID.
  * @return {string} Keyboard overlay ID.
  */
 function getKeyboardOverlayId() {
   return keyboardOverlayId;
 }
@@ skipping 704 matching lines @@
 function onWidgetShown() {
   setTimeout(function() {
     // Show and focus the instructions div after a delay so that chrome vox
     // speaks it correctly.
     $('instructions').style.visibility = 'visible';
     $('instructions').focus();
   }, 500);
 }
 
 document.addEventListener('DOMContentLoaded', init);