Allow features to require optional permissions

Design doc:
https://docs.google.com/document/d/1OhL0Yh7SmWffXyjW_XVQOK95Fqh7gLltk1eEtnKN8Ds/edit

Fixed: twpowertools:86
Change-Id: Iccb22aac2b285307854b7a4c002e9702c24d57f2
diff --git a/src/static/options/options.html b/src/static/options/options.html
index 8a0915a..36fd08a 100644
--- a/src/static/options/options.html
+++ b/src/static/options/options.html
@@ -39,6 +39,7 @@
         </a>
       </div>
       <form>
+        <div id="optional-permissions-warning" hidden data-i18n="optionalpermissionswarning_header"></div>
         <div id="kill-switch-warning" hidden data-i18n="killswitchwarning"></div>
         <div id="options-container"></div>
         <div class="actions"><button id="save" data-i18n="save"></button></div>