Popup is not appearing when used page_action

I am new to Google Chrome extension development. I am having the two following queries

1. Popup is not appearing when I use page_action in manifest.json but appearing when I used browser_action. I would like to know why? Or am I doing wrong

2. Also the icon is showing inactive state. Where as when I use browser_action, the icon is showing in active state (means I could see the color if active, or I could see as black and white icon, when inactive)

Manifest.json

{
  "manifest_version": 2,

  "name": "Getting started example",
  "description": "This extension shows a Google Image search result for the current page",
  "version": "1.0",

  "page_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html",
    "default_title":"getStarted Extension"
  },
  "permissions": [
    "activeTab",
    "https://ajax.googleapis.com/"
  ]
}

UPDATE:

Thanks to Teepemm . Followed his explanation and added the answer with code