Add some missing null checks in chromevox next.

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 05b2009312576a97e48bd8d84413efacd2c26fbd..6f5d24ca154710ed1c949d1a12df3c75c185ebd1 100644
--- a/chrome/browser/resources/chromeos/chromevox/cvox2/background/background.js
+++ b/chrome/browser/resources/chromeos/chromevox/cvox2/background/background.js
@@ -135,10 +135,12 @@ Background.prototype = {
     this.setChromeVoxMode(ChromeVoxMode.FORCE_NEXT);
   },
 
+  /** @type {ChromeVoxMode} */
   get mode() {
     return this.mode_;
   },
 
+  /** @type {cursors.Range} */
   get currentRange() {
     return this.currentRange_;
   },
@@ -595,7 +597,8 @@ Background.prototype = {
       } else {
         // When in compat mode, if the focus is within the desktop tree proper,
         // then do not disable content scripts.
-        if (this.currentRange_.start.node.root.role == 'desktop')
+        if (!this.currentRange_ ||

[David Tseng, 2015/11/17 19:06:25]

this.currentRange_ &&

+            this.currentRange_.start.node.root.role == RoleType.desktop)
           return;
 
         this.disableClassicChromeVox_();