Bug 1447879 - Cannot customize about:preferences#home content when sy…

…nc or preference searching is disabled. r=k88hudson

Have the home preferences page notify when it loads instead of relying on findInPage to trigger sync pane to init.

MozReview-Commit-ID: EJlJDfYBHFO

--HG--
extra : rebase_source : ae5104ec18aefca9241be1b61072b786fa9e6815

browser/components/preferences/in-content/home.js

@@ -372,5 +372,8 @@ let gHomePane = {
       makeDisableControllingExtension(PREF_SETTING_TYPE, HOMEPAGE_OVERRIDE_KEY));
     document.getElementById("disableNewTabExtension").addEventListener("command",
       makeDisableControllingExtension(URL_OVERRIDES_TYPE, NEW_TAB_KEY));
+
+    // Notify observers that the UI is now ready
+    Services.obs.notifyObservers(window, "home-pane-loaded");
   }
 };

browser/extensions/activity-stream/lib/AboutPreferences.jsm

@@ -8,7 +8,7 @@ ChromeUtils.import("resource://gre/modules/Services.jsm");
 ChromeUtils.defineModuleGetter(this, "PluralForm", "resource://gre/modules/PluralForm.jsm");
 const {actionTypes: at} = ChromeUtils.import("resource://activity-stream/common/Actions.jsm", {});
 
-const PREFERENCES_LOADED_EVENT = "sync-pane-loaded";
+const PREFERENCES_LOADED_EVENT = "home-pane-loaded";
 const XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
 
 // These "section" objects are formatted in a way to be similar to the ones from