Convert *.css files to *_style.html files for the following custom elements: date_time_page, setting

chrome/browser/resources/settings/settings_main/settings_main.html

 <link rel="import" href="chrome://resources/polymer/polymer/polymer.html">
 <link rel="import" href="chrome://resources/polymer/core-animated-pages/core-animated-pages.html">
 <link rel="import" href="chrome://resources/polymer/core-transition/core-transition.html">
 <link rel="import" href="chrome://resources/polymer/paper-shadow/paper-shadow.html">
 <link rel="import" href="chrome://md-settings/a11y_page/a11y_page.html">
 <link rel="import" href="chrome://md-settings/date_time_page/date_time_page.html">
 <link rel="import" href="chrome://md-settings/downloads_page/downloads_page.html">
 <link rel="import" href="chrome://md-settings/internet_page/internet_page.html">
 <link rel="import" href="chrome://md-settings/routing/more_routing/more_routing.html">
+<link rel="import" href="settings_main_style.html">
 
 <!-- Drivers manage how the URL is read, and how to navigate to URLs. "path"
      based driver means URLs like /a11y are generated. For more details, see
      http://goo.gl/maQU6V -->
 <more-routing-config driver="path"></more-routing-config>
 <polymer-element name="cr-settings-main">
   <template>
-    <link rel="stylesheet" href="settings_main.css">
+    <core-style ref="settingsMainStyle"></core-style>
     <div id="mainContainer">
       <content select="core-icon-button"></content>
       <more-route-selector>
         <core-animated-pages id="pageContainer" selected="{{selectedPageId}}"
             valueattr="PAGE_ID" transitions="cross-fade">
 <if expr="chromeos">
           <cr-settings-internet-page route="/internet">
           </cr-settings-internet-page>
 </if>
           <cr-settings-a11y-page prefs="{{prefs}}" route="/a11y">
           </cr-settings-a11y-page>
 <if expr="chromeos">
           <cr-settings-date-time-page prefs="{{prefs}}" route="/datetime">
           </cr-settings-date-time-page>
 </if>
           <cr-settings-downloads-page prefs="{{prefs}}" route="/downloads">
           </cr-settings-downloads-page>
         </core-animated-pages>
       </more-route-selector>
     </div>
   </template>
   <script src="settings_main.js"></script>
 </polymer-element>