Prevent Add Exception from showing on the All Sites list.

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

Index: chrome/browser/resources/settings/site_settings/site_list.html
diff --git a/chrome/browser/resources/settings/site_settings/site_list.html b/chrome/browser/resources/settings/site_settings/site_list.html
index 2bbd65e06b06a3f851f812206310e2b8f87a5f7f..306208d869b00fd3d9612b036bab1523ac187dc3 100644
--- a/chrome/browser/resources/settings/site_settings/site_list.html
+++ b/chrome/browser/resources/settings/site_settings/site_list.html
@@ -82,7 +82,7 @@
           </div>
         </template>
 
-        <div class="button-container">
+        <div class="button-container" hidden$="[[allSites]]">

[Dan Beam, 2016/07/06 16:23:27]

nit: it may be worthwhile to use dom-if instead of hidden here because
<paper-button> has a lot of elements used to implement it (it's heavier than you
think)

[Finnur, 2016/07/07 09:50:10]

Fair enough. Done. Checking in.

           <paper-button on-tap="onAddSiteTap_" class="primary-button no-upper">
             $i18n{addSiteLink}
           </paper-button>