fileBrowserHandler

This is for creating applications on ChromeOS that can edit or view specific file types.

Examples:

• An image editor that can open and edit .png and .jpg files directly from the Files app.
• A custom text editor for programmers that handles file types like .js or .py.
• A video player that can play specific media formats.

In addition to the permission, you must define the file_browser_handlers key in the manifest.

{
  "name": "My ChromeOS Text Editor",
  "version": "1.0",
  "manifest_version": 3,
  "permissions": [
    "fileBrowserHandler"
  ],
  "file_browser_handlers": [
    {
      "id": "open",
      "default_title": "Open with My Text Editor",
      "file_filters": [
        "filesystem:*.txt",
        "filesystem:*.md"
      ]
    }
  ]
}

Why is it not risky?

This permission (only for ChromeOS) lets an extension appear in the "Open with" menu for certain files. For example, a photo editor could open .jpg files.

This is safe because the extension can only access files that you explicitly choose to open with it. It does not have general access to your file system and cannot see any other files. You are always in control.

The API is event-based. The service worker listens for the onExecute event.

// background.js

// Listen for when the user selects our handler from the Files app
chrome.fileBrowserHandler.onExecute.addListener((id, details) => {
  if (id === 'open') {
    console.log('File handler executed.');
    console.log('File entries:', details.entries);

    details.entries.forEach(entry => {
      console.log(`Processing file: ${entry.name}`);
      // In a real app, you would open a window and use the
      // File System Access API to read the content of the file entry.
    });
  }
});