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      1 // Copyright (c) 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 /**
      6  * @fileoverview Script that runs on the background page.
      7  */
      8 
      9 CONTENT_SCRIPTS = [
     10   'accessibility_utils.js',
     11   'traverse_util.js',
     12   'caret_browsing.js'
     13 ];
     14 
     15 /**
     16  * The class handling the Caret Browsing background page, which keeps
     17  * track of the current state, handles the browser action button, and
     18  * initializes the content script in all running tabs when the extension
     19  * is first loaded.
     20  * @constructor
     21  */
     22 var CaretBkgnd = function() {};
     23 
     24 /**
     25  * Flag indicating whether caret browsing is enabled. Global, applies to
     26  * all tabs simultaneously.
     27  * @type {boolean}
     28  */
     29 CaretBkgnd.isEnabled;
     30 
     31 /**
     32  * Change the browser action icon and tooltip based on the enabled state.
     33  */
     34 CaretBkgnd.setIcon = function() {
     35   chrome.browserAction.setIcon(
     36       {'path': CaretBkgnd.isEnabled ?
     37                '../caret_19_on.png' :
     38                '../caret_19.png'});
     39   chrome.browserAction.setTitle(
     40       {'title': CaretBkgnd.isEnabled ?
     41                 'Turn Off Caret Browsing (F7)' :
     42                 'Turn On Caret Browsing (F7)' });
     43 };
     44 
     45 /**
     46  * This is called when the extension is first loaded, so that it can be
     47  * immediately used in all already-open tabs. It's not needed for any
     48  * new tabs that open after that, the content script will be automatically
     49  * injected into any new tab.
     50  */
     51 CaretBkgnd.injectContentScripts = function() {
     52   chrome.windows.getAll({'populate': true}, function(windows) {
     53     for (var i = 0; i < windows.length; i++) {
     54       var tabs = windows[i].tabs;
     55       for (var j = 0; j < tabs.length; j++) {
     56         for (var k = 0; k < CONTENT_SCRIPTS.length; k++) {
     57           chrome.tabs.executeScript(
     58               tabs[j].id,
     59               {file: CONTENT_SCRIPTS[k], allFrames: true},
     60               function(result) {
     61                 // Ignore.
     62                 chrome.runtime.lastError;
     63               });
     64         }
     65       }
     66     }
     67   });
     68 };
     69 
     70 /**
     71  * Toggle caret browsing on or off, and update the browser action icon and
     72  * all open tabs.
     73  */
     74 CaretBkgnd.toggle = function() {
     75   CaretBkgnd.isEnabled = !CaretBkgnd.isEnabled;
     76   var obj = {};
     77   obj['enabled'] = CaretBkgnd.isEnabled;
     78   chrome.storage.sync.set(obj);
     79   CaretBkgnd.setIcon();
     80 };
     81 
     82 /**
     83  * Initialize the background script. Set the initial value of the flag
     84  * based on the saved preference in localStorage, update the browser action,
     85  * inject into running tabs, and then set up communication with content
     86  * scripts in tabs. Also check for prefs updates (from the options page)
     87  * and send them to content scripts.
     88  */
     89 CaretBkgnd.init = function() {
     90   chrome.storage.sync.get('enabled', function(result) {
     91     CaretBkgnd.isEnabled = result['enabled'];
     92     CaretBkgnd.setIcon();
     93     CaretBkgnd.injectContentScripts();
     94 
     95     chrome.browserAction.onClicked.addListener(function(tab) {
     96       CaretBkgnd.toggle();
     97     });
     98   });
     99 
    100   chrome.storage.onChanged.addListener(function() {
    101     chrome.storage.sync.get('enabled', function(result) {
    102       CaretBkgnd.isEnabled = result['enabled'];
    103       CaretBkgnd.setIcon();
    104     });
    105   });
    106 };
    107 
    108 CaretBkgnd.init();
    109