Initial checkin of accessibility extensions.

ui/accessibility/extensions/longdesc/background.js

Index: ui/accessibility/extensions/longdesc/background.js
diff --git a/ui/accessibility/extensions/longdesc/background.js b/ui/accessibility/extensions/longdesc/background.js
new file mode 100644
index 0000000000000000000000000000000000000000..5e05eb9c0c18b81a64bec40108899c1de78a24ac
--- /dev/null
+++ b/ui/accessibility/extensions/longdesc/background.js
@@ -0,0 +1,66 @@
+/* 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. */
+
+var ariaDescribedAt = '';
+var longDesc = '';
+
+ /**
+ * 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.
+ */
+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++) {
+      chrome.tabs.executeScript(
+        tabs[j].id,
+        {file: 'lastRightClick.js'});
+    }
+  }
+});
+
+/**
+ * Add context menu item when the extension is installed.
+ */
+chrome.contextMenus.create({
+    "title": "More information...",
+    "contexts": ["all"],
+    "id": "moreInfo",
+    "onclick": contextMenuClicked,
+    "enabled": false
+  });
+
+/**
+ * Add listener for messages from content script.
+ * Enable/disable the context menu item.
+ */
+chrome.runtime.onMessage.addListener(
+  function (request, sender, sendResponse) {
+    if (request.enabled) {
+      ariaDescribedAt = request.ariaDescribedAt;
+      longDesc = request.longDesc;
+    }
+    chrome.contextMenus.update('moreInfo', {
+      "enabled": request.enabled
+    });
+  });
+
+/**
+ * Event handler for when a context menu item is clicked.
+ * aria-describedat is given a higher priority.
+ * No need to strip the URL of leading/trailing white space
+ * because Chrome takes care of this.
+ *
+ * @param info
+ * @param tab
+ */
+function contextMenuClicked(info, tab) {
+  if (ariaDescribedAt !== '') {
+    chrome.tabs.create({url: ariaDescribedAt});
+  } else if (longDesc !== '') {
+    chrome.tabs.create({url: longDesc});
+  }
+}