It is time.

ui/accessibility/extensions/alt/background.js

-// Copyright 2014 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.
-
-function injectScripts(opt_tab) {
-  chrome.tabs.executeScript({
-    file: 'lib/axs_testing.js',
-    allFrames: true
-  }, function() {
-    console.log('successfully injected axs_testing.js');
-    chrome.tabs.executeScript({
-      file: 'hide-images.js',
-      allFrames: true
-    }, function() {
-      console.log('successfully injected script', opt_tab ? opt_tab.url : '');
-      chrome.tabs.insertCSS({
-        file: 'hide-images.css',
-        allFrames: true
-      }, function() {
-        console.log('successfully injected css', opt_tab ? opt_tab.url : '');
-        chrome.tabs.executeScript({
-          code: 'toggleEnabled();',
-          allFrames: true
-        }, function() {
-          console.log('created infobar');
-          chrome.tabs.executeScript({
-            code: 'createInfobar();'
-          });
-        });
-      });
-    });
-  });
-}
-
-chrome.commands.onCommand.addListener(function(command) {
-  console.log('command: ', command);
-  if (command == 'example_keyboard_command') {
-    injectScripts();
-  }
-});
-
-chrome.browserAction.onClicked.addListener(function(tab) {
-  injectScripts(tab);
-});
-