[MD WebUI] Fix sidebar selected color.

chrome/browser/resources/md_extensions/sidebar.html

 <link rel="import" href="chrome://resources/html/cr.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icons/hardware-icons.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icons/iron-icons.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-checkbox/paper-checkbox.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-menu/paper-menu.html">
+<link rel="import" href="chrome://resources/polymer/v1_0/paper-styles/color.html">
 <link rel="import" href="chrome://extensions/icons.html">
 
 <dom-module id="extensions-sidebar">
   <template>
     <style>
       :host {
         margin-top: 30px;
         white-space: nowrap;
       }
 
       #section-menu,
       .section-item {
         -webkit-margin-start: 20px;
       }
 
       #section-menu {
         --paper-menu-background-color: transparent;
         --paper-menu-selected-item: {
           background-color: transparent;
-          color: rgb(66, 133, 244);
+          color: var(--google-blue-700);
           font-weight: normal;
         }
 
         padding: 0;
       }
 
       #more-extensions {
         display: flex;
         text-decoration: none;
       }
 
       paper-item {
         color: #5A5A5A;
         cursor: pointer;
         font-size: 88%;
         padding: 0;
       }
 
       .section-menu-item iron-icon,
       .section-item iron-icon {
         -webkit-margin-end: 15px;
       }
 
       #developer-mode-checkbox {
-        --paper-checkbox-checked-color: rgb(66, 133, 244);
-        --primary-text-color: #5A5A5A;
+        --paper-checkbox-checked-color: var(--google-blue-700);
+        --primary-text-color: #5a5a5a;
       }
 
       #developer-mode {
         display: flex;
       }
 
       #developer-mode span {
         flex-grow: 1;
       }
 
@@ skipping 43 matching lines @@
         </paper-item>
         <paper-item class="section-item" id="update-now"
             on-tap="onUpdateNowTap_">
           <span>$i18n{sidebarUpdateNow}</span>
         </paper-item>
       </template>
     </div>
   </template>
   <script src="chrome://extensions/sidebar.js"></script>
 </dom-module>