Change Chrome New Tab Page to local file

Solution 1:

There is no way to do this besides creating your own extension (see question comments for details). As it turns out, creating your own extension to do so is incredibly easy.

1. Create a new folder
2. Place the HTML file you want to load in your new tab inside it. Mine is called new-tab.html

3. Create another file in the folder called manifest.json that looks like this:

   {
     "name": "My custom new tab page",
     "description": "Overrides the new tab page",
     "version": "0.1",
     "incognito": "split",
     "chrome_url_overrides": {
       "newtab": "new-tab.html"
     },
     "manifest_version": 2
   }
   

4. Go to chrome://extensions and click the Developer mode checkbox on the top right.

5. Click the Load unpacked extension… button

6. Navigate to your folder and click select