HTML and CSS Reference
clipboardWrite , geolocation , notifications , and unlimitedStorage . With the exception of
background, these should be self-explanatory.
The background permission is something special that enables you to continue to run code in the background
even if the app isn't active or hasn't even been launched. This might be useful for multiplayer games to notify
users of actions occurring in the game world even if the user isn't actively playing the game. You can read
more in-depth documentation on the background feature at https://developers.google.com/chrome/apps/docs/
Now copy the icon invasion_128.png into the same directory as the manifest file and you're done!
You can test out the hosted app by loading it as an unpackaged extension. Click the Chrome Wrench menu;
then select the Tools menu and click Extensions.
If you're not already in Developer Mode, click the Developer Mode check box in the top right of the page.
Next, click the Load Unpacked Extension button and find the folder you just created. Click Select. (You are
selecting a folder, not a file, so just single-click the folder and click Select.)
If everything went according to plan, you should see the Alien Invasion extension at the top of the extensions
page with its icon, as shown in Figure 27-1 .
Figure 27-1: The Alien Invasion extension.
If you create a new tab, you should see the Alien Invasion icon in your app screen and you can jump right to
the game by clicking it.
Creating a Packaged App
The difference between a hosted app and a packaged app is simply that the packaged app includes all the files
necessary to run the game in the app directory and points to a local file rather than a web_url .
To create a packaged app from Alien Invasion , you need to create a new directory and copy all the files for
Alien Invasion inside of it.
Next, create a manifest.json file, as shown in Listing 27-2 , and copy the same invasion_128.png icon
into the directory along with an invasion_16.png that serves as the favicon for the app.
Listing 27-2: manifest.json for a packaged app
"name": "Alien Invasion Packaged",
"description": "Save the world, you know the drill...",