ChromeOS: Update styles of material design OOBE.

chrome/browser/resources/chromeos/login/oobe_i18n_dropdown.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/classes/iron-flex-layout.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-iconset-svg/iron-iconset-svg.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-dropdown-menu/paper-dropdown-menu.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-item/paper-item.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-listbox/paper-listbox.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-styles/color.html">
 
 <iron-iconset-svg name="oobe-i18n-dropdown" size="24">
   <svg>
     <defs>
       <!--
       These icons are copied from Polymer's iron-icons and kept in sorted order.
       See http://goo.gl/Y1OdAq for instructions on adding additional icons.
       -->
       <g id="check">
         <path d="M9 16.17L4.83 12l-1.42 1.41L9 19 21 7l-1.41-1.41z">
         </path>
       </g>
     </defs>
   </svg>
 </iron-iconset-svg>
 
 <dom-module id="oobe-i18n-dropdown">
   <template>
-    <style>
-      .selected-icon {
-        color: var(--google-blue-500);
-      } 
-    </style>
+    <link rel="stylesheet" href="oobe_i18n_dropdown.css">
     <paper-dropdown-menu no-label-float>
       <paper-listbox id="listboxDropdown" class="dropdown-content"
           on-iron-select="onSelect_"
           on-iron-deselect="onDeselect_">
         <template is="dom-repeat" id="domRepeat" items="[[items]]">
-          <paper-item item="[[item]]" disabled="[[item.optionGroupName]]">
-            <div class="flex horizontal layout justified">
-              <div hidden="[[item.optionGroupName]]">
+          <paper-item item="[[item]]" disabled="[[item.optionGroupName]]"
+              hr$="[[item.optionGroupName]]">
+            <div class="option-entry flex horizontal layout justified"
+                hidden="[[item.optionGroupName]]">
+              <div class="option-name">
                 [[item.title]]
               </div>
               <iron-icon icon="oobe-i18n-dropdown:check" class="selected-icon"
                   hidden="[[!item.selected]]">
               </iron-icon>
             </div>
-            <hr hidden="[[!item.optionGroupName]]">
+            <div class="hr" hidden="[[!item.optionGroupName]]"></div>
           </paper-item>
         </template>
       </paper-listbox>
     </paper-dropdown-menu>
   </template>
 </dom-module>