Improved isInteresting heuristic, made more AutomationNodes focusable

chrome/browser/resources/chromeos/switch_access/tree_walker.js

 // Copyright 2017 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.
 
 /**
  * Class to move to the appropriate node in the accessibility tree.
  *
  * @constructor
  */
 function AutomationTreeWalker() {};
@@ skipping 98 matching lines @@
     while (node.lastChild)
       node = node.lastChild;
 
     return node;
   },
 
   /**
    * Returns true if |node| is interesting.
    *
    * @param {!chrome.automation.AutomationNode} node
-   * @return {boolean|undefined}
+   * @return {boolean}
    * @private
    */
   isInteresting_: function(node) {
-    return node.state && node.state.focusable;
+    let loc = node.location;
+    let parent = node.parent;
+    let root = node.root;
+    let role = node.role;
+    let state = node.state;
+
+    // Skip things that are offscreen
+    if (state[chrome.automation.StateType.OFFSCREEN]
+        || loc.top < 0 || loc.left < 0)
+      return false;
+
+    if (parent) {
+      // crbug.com/710559
+      // Work around for browser tabs
+      if (role === chrome.automation.RoleType.TAB
+          && parent.role === chrome.automation.RoleType.TAB_LIST
+          && root.role === chrome.automation.RoleType.DESKTOP)
+        return true;
+    }
+
+    // The general rule that applies to everything.
+    return state[chrome.automation.StateType.FOCUSABLE] === true;
   },
 
   /**
    * Return the next sibling of |node| if it has one.
    *
    * @param {chrome.automation.AutomationNode} node
    * @return {chrome.automation.AutomationNode}
    */
   debugMoveToNext: function(node) {
     if (!node)
@@ skipping 62 matching lines @@
     let parent = node.parent;
     if (parent) {
       return parent;
     } else {
       console.log('Node has no parent');
       console.log('\n');
       return null;
     }
   }
 };