redesign and reimplement proxy config service and tracker, revise proxy ui on cros

chrome/browser/resources/options/chromeos/internet_detail.html

 <div id="detailsInternetPage" class="page" hidden>
   <h1 id="inetTitle"></h1>
   <!-- Navigation tabs -->
   <div id="details-tab-strip" class="subpages-nav-tabs">
     <span id="wifiNetworkNavTab" class="tab wifi-details"
         tab-contents="wifiNetworkTab">
       <span class="tab-label"
           i18n-content="wifiNetworkTabLabel"></span>
       <span class="active-tab-label" i18n-content="wifiNetworkTabLabel"></span>
     </span>
@@ skipping 295 matching lines @@
             <list id="ipConfigList"></list>
           </div>
         </div>
       </div>
     </section>
     <section id="change-proxy-section">
       <div>
         <button id="change-proxy-button" i18n-content="changeProxyButton">
         </button>
       </div>
-      <div id="change-proxy-text" hidden></div>
     </section>
   </div>
   <div id="security-tab"
        class="subpages-tab-contents cellular-details gsm-only">
     <div id="cellular-security-options">
       <section>
         <div id="sim-pin-lock" class="checkbox">
          <label>
            <input id="sim-card-lock-enabled" type="checkbox">
            <span i18n-content="lockSimCard"></span>
@@ skipping 13 matching lines @@
     <button id="detailsInternetLogin"
             i18n-content="connect_button"></button>
     <button id="detailsInternetDisconnect"
             i18n-content="disconnect_button"></button>
     <button id="activateDetails"
             i18n-content="activate_button"></button>
     <button id="buyplanDetails"
             i18n-content="buyplan_button"></button>
   </div>
 </div>