### Preflight Checklist
* [x] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/master/CONTRIBUTING.md) for this project.
* [x] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/master/CODE_OF_CONDUCT.md) that this project adheres to.
* [x] I have searched the issue tracker for an issue that matches the one I want to file, without success.

### Issue Details

* **Electron Version:**
10.0.0-nightly.20200220
* **Operating System:**
macOS 10.15.1
* **Last Known Working Electron version:**
I don't know (judging by implementation it never worked)

### Expected Behavior:
Call to BrowserWindow.webContents.focus focuses proper window

### Actual Behavior:
Call  to BrowserWindow.webContents.focus does nothing

### To Reproduce:

Run following simple app:
```
const { app, BrowserWindow } = require('electron')

function createWindow () {
  let win1 = new BrowserWindow({ x:100, y: 300, width: 300, height: 200 })
  win1.on('closed', () => {
    win1 = null
  })
  win1.loadURL('https://github.com')

  let win2 = new BrowserWindow({ x:300, y: 300, width: 300, height: 200 })
  win2.on('closed', () => {
    win1 = null
  })
  win2.loadURL('http://www.example.com')

  setTimeout(() => {
    win1.webContents.focus();
  }, 3000);
}

app.on('ready', createWindow)
```

It works as expected on Windows: it creates two windows and after three seconds it focuses the first one. On mac it doesn't work and call to `webContents.focus` doesn't change the focus (it stays on the second window).
shell/browser/api/electron_api_web_contents.cc
settings.SetStringKey(printing::kSettingHeaderFooterURL, footer);
  } else {
    settings.SetBoolKey(printing::kSettingHeaderFooterEnabled, false);
  }
  // We don't want to allow the user to enable these settings
  // but we need to set them or a CHECK is hit.
  settings.SetIntKey(printing::kSettingPrinterType, printing::kLocalPrinter);
  settings.SetBoolKey(printing::kSettingShouldPrintSelectionOnly, false);
  settings.SetBoolKey(printing::kSettingRasterizePdf, false);
  // Set custom page ranges to print
  std::vector<gin_helper::Dictionary> page_ranges;
  if (options.Get("pageRanges", &page_ranges)) {
    base::Value page_range_list(base::Value::Type::LIST);
    for (auto& range : page_ranges) {
      int from, to;
      if (range.Get("from", &from) && range.Get("to", &to)) {
        base::Value range(base::Value::Type::DICTIONARY);
        range.SetIntKey(printing::kSettingPageRangeFrom, from);
        range.SetIntKey(printing::kSettingPageRangeTo, to);
        page_range_list.Append(std::move(range));
      } else {
        continue;
      }
    }
    if (page_range_list.GetList().size() > 0)
      settings.SetPath(printing::kSettingPageRange, std::move(page_range_list));
  }
  // Duplex type user wants to use.
  printing::DuplexMode duplex_mode;
  options.Get("duplexMode", &duplex_mode);