Move settings_dropdown_menu styling to settings_shared_css.

chrome/browser/resources/settings/site_settings/site_details_permission.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/iron-flex-layout.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.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/html/web_ui_listener_behavior.html">
 <link rel="import" href="/i18n_setup.html">
 <link rel="import" href="/settings_shared_css.html">
 <link rel="import" href="/site_settings/constants.html">
 <link rel="import" href="/site_settings/site_settings_behavior.html">
 <link rel="import" href="/site_settings/site_settings_prefs_browser_proxy.html">
 
 <dom-module id="site-details-permission">
   <template>
     <style include="settings-shared">
       :host {
         display: block;
       }
 
-      paper-dropdown-menu {
-        --paper-input-container-input: {
-          font-size: inherit;
-        };
-
-        --paper-font-caption: {
-          font-size: inherit;
-        }
-      }
-
       .left-column {
         -webkit-margin-start: 15px;
       }
 
       .right-column {
         -webkit-margin-start: 10px;
       }
 
       .permission-header {
         -webkit-margin-start: -1px;
@@ skipping 23 matching lines @@
       </div>
       <div class="flex right-column">
         <div class="permission-header">
           [[computeTitleForContentCategory(category)]]
         </div>
         <div class="permission-list">
           <paper-dropdown-menu>
             <paper-listbox id="permission" class="dropdown-content"
                 on-iron-activate="onPermissionMenuIronActivate_"
                 attr-for-selected="data-permission-value">
-              <paper-item id="allow"
+              <div id="allow" class="dropdown-item" role="option"
                   data-permission-value$="[[PermissionValues.ALLOW]]">
                 [[i18n_.allowAction]]
-              </paper-item>
-              <paper-item id="block"
+              </div>
+              <div id="block" class="dropdown-item" role="option"
                   data-permission-value$="[[PermissionValues.BLOCK]]">
                  [[i18n_.blockAction]]
-              </paper-item>
+              </div>
             </paper-listbox>
           </paper-dropdown-menu>
         </div>
       </div>
     </div>
   </template>
   <script src="site_details_permission.js"></script>
 </dom-module>