chrome/common/extensions/docs/templates/articles/manifest/file_handlers.html

<h1 id="file_handlers">Manifest - File Handlers</h1>

<p>
Used by <a href="../apps/app_lifecycle.html#eventpage">packaged apps</a>
to specify what types of files the app can handle. An app can have multiple <code>file_handlers</code>, with each one having an identifier, a list of MIME types and/or a list of file extensions that can be handled, and
a title. Here's an example of specifying file handlers:
</p>

<pre>
"file_handlers": {
  "text": {
    "types": [
      "text/*"
    ],
    "title": "Text editor"
  },
  "image": {
    "types": [
      "image/png",
      "image/jpeg"
    ],
    "extensions": [
      "tiff"
    ]
    "title": "Image editor"
  },
  "any": {
    "extensions": [
      "*"
    ]
    "title": "Any file type editor"
  }
}
</pre>

<p>
To handle files, apps also need to declare the $ref:fileSystem
permission. Apps can then be passed files in the $ref:app.runtime.onLaunched
event - either from the system
file manager (currently supported on ChromeOS only) or by providing
a path on the <a href="../first_app.html#open">command line</a>.
</p>