Override pages are a way to replace a page that Google Chrome provides with an HTML file that your extension provides. An override page usually has CSS and JavaScript code, in addition to HTML. A single extension can only override one page.

Currently, extensions can replace two pages:

• The New Tab page — the page that appears when the user creates a new tab or window.
• The History page — the page that appears when the user selects the 'History' menu item.

The default New Tab page	An alternative New Tab page

Manifest

Register override pages in the extension manifest using property chrome_url_overrides. For example, the new tabs page can be overridden like this:

{
  "name": "My extension",
  ...
  "chrome_url_overrides": {
    "newtab": "newtab.html"
  },
  ...
}

{
  "name": "My extension",
  ...
  "chrome_url_overrides": {
    "history": "history.html"
  },
  ...
}

Tips

For an effective override pages, follow these guidelines:

• Make your page quick and small.
  Users expect built in browser pages to open instantly. Avoid doing things that may take a long time. For example, avoid synchronous fetches of network or database resources.

• Include a title in your page.
  Otherwise people will see the URL of the page, which might confuse them. Here's an example of specifying the title: <title>New Tab</title>

• Don't rely on the page having the keyboard focus.
  The address bar always gets the focus first when the user creates a new tab.

• Don't try to emulate the default pages.
  The APIs necessary to create a slightly modified version of the default New Tab page — with top pages, recently closed pages, tips, a theme background image, and so on — don't exist yet. Until they do, you're better off trying to make something completely different.

Examples

You can find simple examples of defining override pages in the examples/api/override directory. For other examples and for help in viewing the source code, see Samples.