[chrome-gnome-shell/feature/extensions_sync] Fix constant name

[Yuri Konotopov <ykonotopov src gnome org>]

commit 4bbfc4ae839505f64fc63be9824d56afd5448e27
Author: Yuri Konotopov <ykonotopov gmail com>
Date:   Thu Aug 11 13:27:48 2016 +0300

    Fix constant name

 extension/content-script-start.js |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/extension/content-script-start.js b/extension/content-script-start.js
index 36a2649..b4887c3 100644
--- a/extension/content-script-start.js
+++ b/extension/content-script-start.js
@@ -61,7 +61,7 @@ chrome.runtime.onMessage.addListener(
        function (request, sender, sendResponse) {
                if(
                        sender.id && sender.id === GS_CHROME_ID &&
-                       request && request.signal && [SIGNAL_EXTENSIONS_CHANGED, 
SIGNAL_SHELL_APPEARED].indexOf(request.signal) !== -1)
+                       request && request.signal && [SIGNAL_EXTENSION_CHANGED, 
SIGNAL_SHELL_APPEARED].indexOf(request.signal) !== -1)
                {
                        window.postMessage(
                                {