Complete live region support in ChromeVox Next.

chrome/common/extensions/api/automation.idl

 // 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.
 
 // The <code>chrome.automation</code> API allows developers to access the
 // automation (accessibility) tree for the browser. The tree resembles the DOM
 // tree, but only exposes the <em>semantic</em> structure of a page. It can be
 // used to programmatically interact with a page by examining names, roles, and
 // states, listening for events, and performing actions on nodes.
 [nocompile] namespace automation {
@@ skipping 299 matching lines @@
 
   // A change to the Automation tree.
   [nocompile, noinline_doc] dictionary TreeChange {
     // The $(ref:automation.AutomationNode) that changed.
     AutomationNode target;
 
     // The type of change.
     TreeChangeType type;
   };
 
+  // Possible tree changes to listen to using addTreeChangeObserver.
+  // Note that listening to all tree changes can be expensive.
+  enum TreeChangeObserverFilter {
+    noTreeChanges,
+    liveRegionTreeChanges,
+    allTreeChanges
+  };
+
   // A listener for changes on the <code>AutomationNode</code> tree.
   callback TreeChangeObserver = void(TreeChange treeChange);
 
   // A single node in an Automation tree.
   [nocompile, noinline_doc] dictionary AutomationNode {
     // The root node of the tree containing this AutomationNode.
     AutomationNode root;
 
     // Whether this AutomationNode is a root node.
     boolean isRootNode;
@@ skipping 242 matching lines @@
     // tree with a placeholder root node; listen for the "loadComplete" event to
     // get a notification that the tree has fully loaded (the previous root node
     // reference will stop working at or before this point).
     [nocompile] static void getTree(optional long tabId, RootCallback callback);
 
     // Get the automation tree for the whole desktop which consists of all on
     // screen views. Note this API is currently only supported on Chrome OS.
     [nocompile] static void getDesktop(RootCallback callback);
 
     // Add a tree change observer. Tree change observers are static/global, they
-    // listen to changes across all trees.
+    // listen to changes across all trees. Pass a filter to determine what
+    // specific tree changes to listen to, and note that listnening to all
+    // tree changes can be expensive.
     [nocompile] static void addTreeChangeObserver(
-        TreeChangeObserver observer);
+        TreeChangeObserverFilter filter, TreeChangeObserver observer);
 
     // Remove a tree change observer.
     [nocompile] static void removeTreeChangeObserver(
         TreeChangeObserver observer);
 
     // Sets the selection in a tree. This creates a selection in a single
     // tree (anchorObject and focusObject must have the same root).
     // Everything in the tree between the two node/offset pairs gets included
     // in the selection. The anchor is where the user started the selection,
     // while the focus is the point at which the selection gets extended
     // e.g. when dragging with a mouse or using the keyboard. For nodes with
     // the role staticText, the offset gives the character offset within
     // the value where the selection starts or ends, respectively.
     [nocompile] static void setDocumentSelection(
         SetDocumentSelectionParams params);
   };
 };