Initial checkin of accessibility extensions.

ui/accessibility/extensions/caretbrowsing/background.js

+// Copyright (c) 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.
+
+/**
+ * @fileoverview Script that runs on the background page.
+ */
+
+CONTENT_SCRIPTS = [
+  'accessibility_utils.js',
+  'traverse_util.js',
+  'caret_browsing.js'
+];
+
+/**
+ * The class handling the Caret Browsing background page, which keeps
+ * track of the current state, handles the browser action button, and
+ * initializes the content script in all running tabs when the extension
+ * is first loaded.
+ * @constructor
+ */
+var CaretBkgnd = function() {};
+
+/**
+ * Flag indicating whether caret browsing is enabled. Global, applies to
+ * all tabs simultaneously.
+ * @type {boolean}
+ */
+CaretBkgnd.isEnabled;
+
+/**
+ * Change the browser action icon and tooltip based on the enabled state.
+ */
+CaretBkgnd.setIcon = function() {
+  chrome.browserAction.setIcon(
+      {'path': CaretBkgnd.isEnabled ?
+               '../caret_19_on.png' :
+               '../caret_19.png'});
+  chrome.browserAction.setTitle(
+      {'title': CaretBkgnd.isEnabled ?
+                'Turn Off Caret Browsing (F7)' :
+                'Turn On Caret Browsing (F7)' });
+};
+
+/**
+ * This is called when the extension is first loaded, so that it can be
+ * immediately used in all already-open tabs. It's not needed for any
+ * new tabs that open after that, the content script will be automatically
+ * injected into any new tab.
+ */
+CaretBkgnd.injectContentScripts = function() {
+  chrome.windows.getAll({'populate': true}, function(windows) {
+    for (var i = 0; i < windows.length; i++) {
+      var tabs = windows[i].tabs;
+      for (var j = 0; j < tabs.length; j++) {
+        for (var k = 0; k < CONTENT_SCRIPTS.length; k++) {
+          chrome.tabs.executeScript(
+              tabs[j].id,
+              {file: CONTENT_SCRIPTS[k], allFrames: true},
+              function(result) {
+                // Ignore.
+                chrome.runtime.lastError;
+              });
+        }
+      }
+    }
+  });
+};
+
+/**
+ * Toggle caret browsing on or off, and update the browser action icon and
+ * all open tabs.
+ */
+CaretBkgnd.toggle = function() {
+  CaretBkgnd.isEnabled = !CaretBkgnd.isEnabled;
+  var obj = {};
+  obj['enabled'] = CaretBkgnd.isEnabled;
+  chrome.storage.sync.set(obj);
+  CaretBkgnd.setIcon();
+};
+
+/**
+ * Initialize the background script. Set the initial value of the flag
+ * based on the saved preference in localStorage, update the browser action,
+ * inject into running tabs, and then set up communication with content
+ * scripts in tabs. Also check for prefs updates (from the options page)
+ * and send them to content scripts.
+ */
+CaretBkgnd.init = function() {
+  chrome.storage.sync.get('enabled', function(result) {
+    CaretBkgnd.isEnabled = result['enabled'];
+    CaretBkgnd.setIcon();
+    CaretBkgnd.injectContentScripts();
+
+    chrome.browserAction.onClicked.addListener(function(tab) {
+      CaretBkgnd.toggle();
+    });
+  });
+
+  chrome.storage.onChanged.addListener(function() {
+    chrome.storage.sync.get('enabled', function(result) {
+      CaretBkgnd.isEnabled = result['enabled'];
+      CaretBkgnd.setIcon();
+    });
+  });
+};
+
+CaretBkgnd.init();