Improve braille related message descriptions and clean up message handling in Chromevox.

chrome/browser/resources/chromeos/chromevox/walkers/layout_line_walker.js

 // Copyright 2014 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.
 
 /**
  * @fileoverview A JavaScript class for walking lines consisting of one or more
  * clickable nodes.
  */
 
 
@@ skipping 112 matching lines @@
     this.appendBraille_(prevSel, absSel, cur, braille);
   }
   return braille;
 };
 
 
 /**
  * @override
  */
 cvox.LayoutLineWalker.prototype.getGranularityMsg = function() {
-  return cvox.ChromeVox.msgs.getMsg('layout_line');
+  return Msgs.getMsg('layout_line');
 };
 
 
 /**
  * Compares two selections and determines if the lie on the same horizontal
  * line as determined by their bounding rectangles.
  * @param {!cvox.CursorSelection} lSel Left selection.
  * @param {!cvox.CursorSelection} rSel Right selection.
  * @return {boolean} Whether lSel and rSel are on different visual lines.
  * @private
@@ skipping 92 matching lines @@
   if (sel && cur.absEquals(sel)) {
     if (valueSelectionSpan) {
       braille.startIndex = nodeStart + item.getSpanStart(valueSelectionSpan);
       braille.endIndex = nodeStart + item.getSpanEnd(valueSelectionSpan);
     } else {
       braille.startIndex = nodeStart;
       braille.endIndex = nodeStart + 1;
     }
   }
 };