[chrome-gnome-shell/feature/extensions_sync] Added a few comments

[Yuri Konotopov <ykonotopov src gnome org>]

commit d799d8af0b128a8836a2f221fc1a76ed046d2b8e
Author: Yuri Konotopov <ykonotopov gmail com>
Date:   Thu Aug 11 12:15:03 2016 +0300

    Added a few comments

 extension/extension.js |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)
---
diff --git a/extension/extension.js b/extension/extension.js
index a37b2e7..54272c5 100644
--- a/extension/extension.js
+++ b/extension/extension.js
@@ -69,15 +69,24 @@ chrome.runtime.onMessageExternal.addListener(function (request, sender, sendResp
 
 var lastPortMessage = {message: null, date: 0};
 var port = chrome.runtime.connectNative(NATIVE_HOST);
+/*
+ * Native host messaging events handler.
+ */
 port.onMessage.addListener(function (message) {
        if (message && message.signal && [SIGNAL_EXTENSION_CHANGED, 
SIGNAL_SHELL_APPEARED].indexOf(message.signal) !== -1)
        {
+               /*
+                * Skip duplicate events. This is happens eg when extension is installed.
+                */
                if((new Date().getTime()) - lastPortMessage.date < 500 && GSC.isSignalsEqual(message, 
lastPortMessage.message))
                {
                        lastPortMessage.date = new Date().getTime();
                        return;
                }
 
+               /*
+                * Send events to opened extensions.gnome.org tabs
+                */
                chrome.tabs.query({
                        url: EXTENSIONS_WEBSITE + '*'
                },