Remove support for the keygen tag

chrome/browser/resources/settings/privacy_page/privacy_page.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/cr_elements/policy/cr_policy_vars_css.html">
 <link rel="import" href="chrome://resources/html/web_ui_listener_behavior.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/iron-flex-layout-classes.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/neon-animation/neon-animatable.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button-light.html">
 <link rel="import" href="/clear_browsing_data_dialog/clear_browsing_data_dialog.html">
 <link rel="import" href="/controls/settings_checkbox.html">
 <link rel="import" href="/controls/settings_toggle_button.html">
@@ skipping 295 matching lines @@
           <button class="icon-help subpage-title-extra"
               is="paper-icon-button-light" on-tap="onHelpTap_"></button>
           <category-default-setting
               category="{{ContentSettingsTypes.JAVASCRIPT}}">
           </category-default-setting>
           <category-setting-exceptions
               category="{{ContentSettingsTypes.JAVASCRIPT}}">
           </category-setting-exceptions>
         </settings-subpage>
       </template>
-      <template is="dom-if" route-path="/content/keygen" no-search>
-        <settings-subpage page-title="$i18n{siteSettingsKeygen}">
-          <button class="icon-help subpage-title-extra"
-              is="paper-icon-button-light" on-tap="onHelpTap_"></button>
-          <category-default-setting category="{{ContentSettingsTypes.KEYGEN}}">
-          </category-default-setting>
-          <category-setting-exceptions
-              category="{{ContentSettingsTypes.KEYGEN}}">
-          </category-setting-exceptions>
-        </settings-subpage>
-      </template>
       <template is="dom-if" route-path="/content/microphone" no-search>
         <settings-subpage page-title="$i18n{siteSettingsCategoryMicrophone}">
           <button class="icon-help subpage-title-extra"
               is="paper-icon-button-light" on-tap="onHelpTap_"></button>
           <media-picker type="mic"></media-picker>
           <category-default-setting category="{{ContentSettingsTypes.MIC}}">
           </category-default-setting>
           <category-setting-exceptions category="{{ContentSettingsTypes.MIC}}">
           </category-setting-exceptions>
         </settings-subpage>
@@ skipping 69 matching lines @@
             $i18n{siteSettingsCookieRemoveAll}
           </paper-button>
           <site-data-details-subpage page-title="{{pageTitle}}">
           </site-data-details-subpage>
         </settings-subpage>
       </template>
     </settings-animated-pages>
   </template>
   <script src="privacy_page.js"></script>
 </dom-module>