Work around for content select not supporting touch events on it's children.

ui/keyboard/resources/main.js

 // Copyright 2013 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.
 
 var onResize = function() {
   var x = window.innerWidth;
   var y = window.innerHeight;
   var height =  (x > ASPECT_RATIO * y) ? y : Math.floor(x / ASPECT_RATIO);
   keyboard.style.height = height + 'px';
   keyboard.style.width = Math.floor(ASPECT_RATIO * height) + 'px';
@@ skipping 35 matching lines @@
 /**
   * Flatten the keysets which represents a keyboard layout. It has two steps:
   * 1) Replace all kb-key-import elements with imported document that associated
   *   with linkid.
   * 2) Replace all kb-key-sequence elements with generated DOM structures.
   * @param {!Document} content Document to process.
   */
 function flattenKeysets(content) {
   var importedContent = importHTML(content);
   expandHTML(importedContent);
+  var rows = importedContent.querySelectorAll('kb-row');
+  for (var i = 0 ; i < rows.length; i++) {
+    var allKeys = rows[i].children;
+    for (var j = 0; j< allKeys.length; j++) {
+      var weight = allKeys[j].getAttribute('weight');
+      if (weight)
+        allKeys[j].style.webkitBoxFlex = weight;
+    }
+  }
   return importedContent;
 }
 
 addEventListener('resize', onResize);
 
 addEventListener('load', onResize);
 
 // Prevents all default actions of touch. Keyboard should use its own gesture
 // recognizer.
 addEventListener('touchstart', function(e) { e.preventDefault() });
 addEventListener('touchend', function(e) { e.preventDefault() });
 addEventListener('touchmove', function(e) { e.preventDefault() });