Restore focus when an automation node becomes invalidated.

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

Index: chrome/browser/resources/chromeos/chromevox/cvox2/background/background.js
diff --git a/chrome/browser/resources/chromeos/chromevox/cvox2/background/background.js b/chrome/browser/resources/chromeos/chromevox/cvox2/background/background.js
index 1a1bc5cf5ab85179e5840756ad457ee266f9aa89..ef6b8e9ecf0eb59cae0720ff9d39bb9f55f7259d 100644
--- a/chrome/browser/resources/chromeos/chromevox/cvox2/background/background.js
+++ b/chrome/browser/resources/chromeos/chromevox/cvox2/background/background.js
@@ -280,6 +280,15 @@ Background.prototype = {
     if (!newRange)
       return;
 
+    // Is the range invalid?
+    if (newRange.start.node.role === undefined ||

[dmazzoni, 2016/03/16 23:48:36]

Consider ending an excursion if necessary?

[David Tseng, 2016/03/17 00:40:11]

I don't think we want this. For example, in an incremental search, if we
navigate to an element that gets destroyed after we set it as a current range,
we still want to stay in excursion, but just move somewhere valid.

+        newRange.end.node.role === undefined) {
+      // Restore range to the focused location.
+      chrome.automation.getFocus(function(f) {
+        newRange = cursors.Range.fromNode(f);
+      });
+    }
+
     if (!this.inExcursion_)
       this.savedRange_ = new cursors.Range(newRange.start, newRange.end);