Better work around for Blink selection issues.

chrome/browser/resources/chromeos/chromevox/cvox2/background/cursors.js

Index: chrome/browser/resources/chromeos/chromevox/cvox2/background/cursors.js
diff --git a/chrome/browser/resources/chromeos/chromevox/cvox2/background/cursors.js b/chrome/browser/resources/chromeos/chromevox/cvox2/background/cursors.js
index b855f90952ceefe7645cd876159344e5175d1d11..a438d5cf6f64c71975c849abda70849865f68114 100644
--- a/chrome/browser/resources/chromeos/chromevox/cvox2/background/cursors.js
+++ b/chrome/browser/resources/chromeos/chromevox/cvox2/background/cursors.js
@@ -165,17 +165,29 @@ cursors.Cursor.prototype = {
         adjustedIndex += sibling.name.length;
         sibling = sibling.previousSibling;
       }
+    }
 
+    if (this.selectionNode_ && AutomationPredicate.text(this.selectionNode_)) {
       // Work around Blink's somewhat unexpected offset calculation which
-      // requires us to consider all previous siblings of the parenting static
-      // text.
-      var parent = this.node.parent;
-      if (parent.role == RoleType.staticText) {
-        sibling = parent.previousSibling;
-        while (sibling) {
-          if (sibling.name)
-            adjustedIndex += sibling.name.length;
-          sibling = sibling.previousSibling;
+      // requires us to consider all previous siblings of the parenting node of
+      // the static text.
+
+      var parent = this.selectionNode_.parent;
+      if (parent) {
+        // Grab all of the text nodes and accumulate their lengths up to
+        // but not including the current static text node.
+        var texts = [];
+        AutomationUtil.findNodePre(parent, Dir.FORWARD, function(node) {
+          if (AutomationPredicate.text(node))
+            texts.push(node);
+          return false;
+        });
+
+        for (var i = 0; i < texts.length; i++) {
+          if (texts[i] == this.selectionNode_)
+            break;
+
+          adjustedIndex += texts[i].name.length;
         }
       }
     } else if (this.index_ == cursors.NODE_INDEX) {
@@ -588,19 +600,10 @@ cursors.Range.prototype = {
     if (!startNode || !endNode)
       return;
 
-    // Find the most common root.
-    var uniqueAncestors = AutomationUtil.getUniqueAncestors(startNode, endNode);
-    var mcr = startNode.root;
-    if (uniqueAncestors) {
-      var common = uniqueAncestors.pop().parent;
-      if (common)
-        mcr = common.root;
-    }
-
-    if (!mcr || mcr.role == RoleType.desktop)
-      return;
-
-    if (mcr === startNode.root && mcr === endNode.root) {
+    // Only allow selections inside of the same web tree.
+    if (startNode.root &&
+        startNode.root.role == RoleType.rootWebArea &&
+        startNode.root === endNode.root) {
       var startIndex = this.start.selectionIndex_;
 
       // We want to adjust to select the entire node for node offsets;