manifest.json

{
  "manifest_version": 2,

  "name": "Lowder",
  "description": "Decrease volume from tabs, except current.",
  "version": "1.0",

  "background": {
    "scripts" : ["js/background.js"],
    "persistent" : false
  },

  "icons": {
    "19" : "img/icon.png",
    "38" : "img/icon.png",
    "48" : "img/icon.png",
    "128" : "img/icon.png"
  },

  "browser_action": {
    "default_icon": {
      "19" : "img/icon.png",
      "38" : "img/icon.png",
      "48" : "img/icon.png",
      "128" : "img/icon.png"
    },
    "default_popup": "popup.html"
  },

  "content_scripts": [
    {
      "js": ["js/jquery-1.11.2.js", "js/inject.js"],
      "matches": ["<all_urls>"],
      "css": ["css/inject.css"],
      "run_at": "document_start",
      "all_frames": true      
    }
  ],

  "commands": {

    "play" : {
      "suggested_key": {
        "default": "Alt+Shift+K", 
        "mac": "Alt+Shift+K"
      },
      "description": "play tab media"
    },

    "stop" : {
      "suggested_key": {
        "default": "Alt+Shift+X", 
        "mac": "Alt+Shift+X"
      },
      "description": "stop tab media"
    },

    "_execute_browser_action": {
      "suggested_key": {
        "default": "Ctrl+Shift+X",
        "mac": "Ctrl+Shift+X"
      }
    }

  },

  "permissions": [
    "storage",
    "background",
    "tabs",
    "activeTab",
    "notifications",
    "<all_urls>"  
  ]

}