[Sync] Enable searching sync setup overlay from settings

Add customize-sync as the associatedControl of the sync setup overlay, enabling
the search page to check its contents.

BUG=174043


Review URL: https://chromiumcodereview.appspot.com/12209076

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@182019 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/resources/options/options.js

@@ -164,7 +164,8 @@ function load() {
   OptionsPage.registerOverlay(StartupOverlay.getInstance(),
                               BrowserOptions.getInstance());
   OptionsPage.registerOverlay(SyncSetupOverlay.getInstance(),
-                              BrowserOptions.getInstance());
+                              BrowserOptions.getInstance(),
+                              [$('customize-sync')]);
   if (cr.isChromeOS) {
     OptionsPage.registerOverlay(AccountsOptions.getInstance(),
                                 BrowserOptions.getInstance(),