Remove the BackspaceGoesBack flag.

chrome/browser/ui/webui/chromeos/keyboard_overlay_ui.cc

 // 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 "chrome/browser/ui/webui/chromeos/keyboard_overlay_ui.h"
 
 #include <stddef.h>
 
 #include "ash/shell.h"
 #include "base/bind.h"
@@ skipping 298 matching lines @@
                     base::UTF8ToUTF16(kLearnMoreURL));
   source->AddBoolean("keyboardOverlayHasChromeOSDiamondKey",
                      base::CommandLine::ForCurrentProcess()->HasSwitch(
                          chromeos::switches::kHasChromeOSDiamondKey));
   source->AddBoolean("keyboardOverlayTopRowKeysAreFunctionKeys",
                      TopRowKeysAreFunctionKeys(profile));
   ash::Shell* shell = ash::Shell::Get();
   display::DisplayManager* display_manager = shell->display_manager();
   source->AddBoolean("keyboardOverlayIsDisplayUIScalingEnabled",
                      display_manager->IsDisplayUIScalingEnabled());
-  source->AddBoolean(
-      "backspaceGoesBackFeatureEnabled",
-      base::FeatureList::IsEnabled(features::kBackspaceGoesBackFeature));

[michaelpg, 2017/05/10 23:41:51]

Looks like you can remove some #include's, as there are no other uses of the
features namespace or base::FeatureList in this file:
 - chrome_features.h
 - feature_list.h

Check the other files in this CL for the same thing.

[ojan, 2017/05/11 00:53:28]

Pretty sure you caught the two files left that I missed. Sorry about that.

   source->SetJsonPath("strings.js");
   source->AddResourcePath("keyboard_overlay.js", IDR_KEYBOARD_OVERLAY_JS);
   source->SetDefaultResource(IDR_KEYBOARD_OVERLAY_HTML);
   return source;
 }
 
 }  // namespace
 
 // The handler for Javascript messages related to the "keyboardoverlay" view.
 class KeyboardOverlayHandler
@@ skipping 95 matching lines @@
 
 KeyboardOverlayUI::KeyboardOverlayUI(content::WebUI* web_ui)
     : WebDialogUI(web_ui) {
   Profile* profile = Profile::FromWebUI(web_ui);
   web_ui->AddMessageHandler(base::MakeUnique<KeyboardOverlayHandler>(profile));
 
   // Set up the chrome://keyboardoverlay/ source.
   content::WebUIDataSource::Add(profile,
                                 CreateKeyboardOverlayUIHTMLSource(profile));
 }