[Sync UI] Disable the "Advanced..." button when there is an unrecoverable sync error.

chrome/browser/resources/options/personal_options.js

Index: chrome/browser/resources/options/personal_options.js
diff --git a/chrome/browser/resources/options/personal_options.js b/chrome/browser/resources/options/personal_options.js
index 23483d01a22fd0f27e2d2e8adac4a2c5a06e742a..1ca3db5e98865e03d725d1aebeb36d34a5206ad4 100644
--- a/chrome/browser/resources/options/personal_options.js
+++ b/chrome/browser/resources/options/personal_options.js
@@ -176,6 +176,10 @@ cr.define('options', function() {
                 $('sync-status').classList.remove('sync-error');
     },
 
+    setCustomizeSyncButtonEnabled_: function(enabled) {
+      $('customize-sync').disabled = !enabled;
+    },
+
     setSyncActionLinkEnabled_: function(enabled) {
       $('sync-action-link').disabled = !enabled;
     },
@@ -315,6 +319,7 @@ cr.define('options', function() {
   [
     'hideSyncSection',
     'setAutoLoginVisible',
+    'setCustomizeSyncButtonEnabled',
     'setGtkThemeButtonEnabled',
     'setProfilesInfo',
     'setProfilesSectionVisible',