[MD extensions] remove use of paper-menu

This Cl replaces the use of paper-menu in MD extensions with an
iron-selector

Bug: 779282
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I424fbced792781e1ad2a063ab50ce9a93f156660
Reviewed-on: https://chromium-review.googlesource.com/762107Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: Dave Schuyler <dschuyler@chromium.org>
Cr-Commit-Position: refs/heads/master@{#515466}

chrome/browser/resources/md_extensions/sidebar.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 
 <link rel="import" href="chrome://resources/html/cr.html">
+<link rel="import" href="chrome://resources/polymer/v1_0/iron-selector/iron-selector.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button-light.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="navigation_helper.html">
 
@@ -16,6 +16,10 @@
         white-space: nowrap;
       }
 
+      iron-selector .iron-selected {
+        color: var(--google-blue-700);
+      }
+
       #section-menu {
         --paper-menu-background-color: transparent;
         --paper-menu-selected-item: {
@@ -53,7 +57,7 @@
         width: 15px;
       }
     </style>
-    <paper-menu id="section-menu" selected="{{selected_}}">
+    <iron-selector id="sectionMenu">
       <div class="section-item" id="sections-extensions"
           on-tap="onExtensionsTap_">
         $i18n{sidebarExtensions}
@@ -62,7 +66,7 @@
           on-tap="onKeyboardShortcutsTap_">
         $i18n{keyboardShortcuts}
       </div>
-    </paper-menu>
+    </iron-selector>
     <a class="section-item" id="more-extensions" target="_blank"
         href="$i18n{getMoreExtensionsUrl}">
       <span>$i18n{getMoreExtensions}</span>

chrome/browser/resources/md_extensions/sidebar.js

@@ -5,22 +5,15 @@ cr.define('extensions', function() {
   const Sidebar = Polymer({
     is: 'extensions-sidebar',
 
-    properties: {
-      /** @private {number} */
-      selected_: {
-        type: Number,
-        value: -1,
-      },
-    },
-
     hostAttributes: {
       role: 'navigation',
     },
 
     /** @override */
     attached: function() {
-      this.selected_ =
-          extensions.navigation.getCurrentPage().page == Page.SHORTCUTS ? 1 : 0;
+      this.$.sectionMenu.select(
+          extensions.navigation.getCurrentPage().page == Page.SHORTCUTS ? 1 :
+                                                                          0);
     },
 
     /** @private */