MD Settings: Improve rendering performance of fonts page.

chrome/browser/resources/settings/controls/settings_dropdown_menu.html

 <link rel="import" href="chrome://resources/html/polymer.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-item/paper-item-shared-styles.html">

[michaelpg, 2016/06/29 19:49:14]

alphabetize

[dpapad, 2016/06/29 20:50:08]

Done.

 <link rel="import" href="/controls/pref_control_behavior.html">
 <link rel="import" href="/i18n_setup.html">
 <link rel="import" href="/prefs/pref_util.html">
 <link rel="import" href="/settings_shared_css.html">
 
 <dom-module id="settings-dropdown-menu">
   <template>
-    <style include="settings-shared">
-      paper-item {
+    <style include="settings-shared paper-item-shared-styles">
+      .paper-item {
         color: var(--paper-grey-800);
         font-size: inherit;
       }
 
       paper-dropdown-menu {
         --iron-icon-fill-color: var(--paper-grey-600);
         --paper-font-subhead: {
           font-size: inherit;
         };
         --paper-input-container-underline: {
           background: var(--paper-grey-300);
         };
         width: 160px;
       }
      </style>
     <paper-dropdown-menu id="dropdownMenu" label="[[menuLabel_]]"
         on-iron-select="onSelect_" no-label-float$="[[noLabelFloat]]"
         disabled="[[shouldDisableMenu_(disabled, menuOptions.*)]]">
       <paper-listbox class="dropdown-content" selected="{{selected_}}"
           attr-for-selected="data-value">
-        <template is="dom-repeat" items="[[menuOptions]]">
-          <paper-item data-value$="[[item.value]]">[[item.name]]</paper-item>
+        <template is="dom-repeat" items="[[menuOptions]]" item-count="5">
+          <button class="paper-item"

[michaelpg, 2016/06/29 19:49:14]

the docs suggest including role="option". i assume that's an a11y thing but
haven't looked into it... is there a reason you dropped it?

[dpapad, 2016/06/29 20:50:08]

Done, just forgot about it.

+            data-value$="[[item.value]]">[[item.name]]</button>

[michaelpg, 2016/06/29 19:49:14]

4-space indent
nit: line break after > and before </button> like lines 38-41

[dpapad, 2016/06/29 20:50:08]

Fixed.

         </template>
-        <paper-item data-value$="[[notFoundValue_]]"
+        <button class="paper-item" data-value$="[[notFoundValue_]]"
             hidden$="[[!isSelectedNotFound_(selected_)]]">
           $i18n{custom}
-        </paper-item>
+        </button>
       </paper-listbox>
     </paper-dropdown-menu>
   </template>
   <script src="settings_dropdown_menu.js"></script>
 </dom-module>