Site Settings Desktop: Support SessionOnly for cookies on Site Details page.

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-icon/iron-icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-dropdown-menu/paper-dropdown-menu-light.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="/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">
 
@@ skipping 15 matching lines @@
               on-iron-activate="onPermissionMenuIronActivate_"
               attr-for-selected="data-permission-value">
             <button id="allow" class="dropdown-item" role="option"
                 data-permission-value$="[[PermissionValues.ALLOW]]">
               $i18n{siteSettingsActionAllow}
             </button>
             <button id="block" class="dropdown-item" role="option"
                 data-permission-value$="[[PermissionValues.BLOCK]]">
               $i18n{siteSettingsActionBlock}
             </button>
+            <button id="sessionOnly" class="dropdown-item" role="option"
+                data-permission-value$="[[PermissionValues.SESSION_ONLY]]"
+                hidden$="[[!isCookiesCategory_(category)]]">
+              $i18n{siteSettingsActionSessionOnly}
+            </button>
           </paper-listbox>
         </paper-dropdown-menu-light>
       </div>
     </div>
   </template>
   <script src="site_details_permission.js"></script>
 </dom-module>