Add shortcuts to save and load

[Bartleby2718]

https://developer.chrome.com/extensions/commands#usage

[Bartleby2718]

This issue wasn't solved in the commit. Must have deleted the code when I made a commit.

[Bartleby2718]

Memo

https://itnext.io/create-chrome-extension-with-reactjs-using-inject-page-strategy-137650de1f39
3. Injecting a React app to page as content script

• npm run eject -> make a commit here once
• npm install
• In webpack.config.js: (Make extension compatible with Create React App v2.x satendra02/react-chrome-extension#2)
  • Change entry and output
  • Set runtimeChunk: false,
  • Remove .[contenthash:8] and [chunkhash:8] here and there
• Update manifest.json

[Bartleby2718]

"background": {
    "scripts": ["background.js"],
    "persistent": false
  },

chrome.commands.onCommand.addListener(function (command) {
    if (command = 'save') {
        saveClicked();
    }
    else if (command = 'load') {
        loadClicked();
    }
});

[Bartleby2718]

Test on Macs before releasing.

[jeongm-in]

@jeongm-in