Support selection and copying over non-editable content in ChromeVox Next.

chrome/browser/resources/chromeos/chromevox/common/chrome_extension_externs.js

Index: chrome/browser/resources/chromeos/chromevox/common/chrome_extension_externs.js
diff --git a/chrome/browser/resources/chromeos/chromevox/common/chrome_extension_externs.js b/chrome/browser/resources/chromeos/chromevox/common/chrome_extension_externs.js
index 5d8213dbbff48dbd786384a003e9f7bca9f4bea4..de3926217366d97813655d5e8fb2ae76231ceb99 100644
--- a/chrome/browser/resources/chromeos/chromevox/common/chrome_extension_externs.js
+++ b/chrome/browser/resources/chromeos/chromevox/common/chrome_extension_externs.js
@@ -430,7 +430,7 @@ chrome.automation.AutomationNode.prototype.wordEnds;
 
 
 /**
- * @type {chrome.automation.AutomationNode}
+ * @type {chrome.automation.AutomationRootNode}
  */
 chrome.automation.AutomationNode.prototype.root;
 
@@ -618,5 +618,31 @@ chrome.automation.focusOffset;
  */
 chrome.automation.AutomationNode.prototype.activeDescendant;
 
+/**
+ * @extends {chrome.automation.AutomationNode}
+ * @constructor
+ */
+chrome.automation.AutomationRootNode = function() {};
+
+/**
+ * @type {chrome.automation.AutomationNode}
+ */
+chrome.automation.AutomationRootNode.prototype.anchorObject;
+
+/**
+ * @type {number}
+ */
+chrome.automation.AutomationRootNode.prototype.anchorOffset;
+
+/**
+ * @type {chrome.automation.AutomationNode}
+ */
+chrome.automation.AutomationRootNode.prototype.focusObject;
+
+/**
+ * @type {number}
+ */
+chrome.automation.AutomationRootNode.prototype.focusOffset;
+
 /** @type {function() : !Object} */
 chrome.app.getDetails;