### 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:**
  * 10.1.1
* **Operating System:**
  * macOS 10.15.4

We recently started launching as hidden on macOS (that is, `show: false` or `browserWindow.hide()` while loading the page, followed by `browserWindow.show()` when the dock icon is clicked). This results in some busted focus behavior on the first activation of the window. The second activation restores it.

### Expected Behavior
The guest page receives a `focus` event on the first activation of the app, when created with `show: false`.

### Actual Behavior
The guest page doesn't receive the first `focus` event. Subsequent activations do trigger a `focus` event.

### To Reproduce
[Electron Fiddle](https://gist.github.com/CharlieHess/c507468cd40630d04f58c6514100b997)

shell/browser/api/electron_api_web_contents.cc
frame_subscriber_.reset();
}
void WebContents::StartDrag(const gin_helper::Dictionary& item,
                            gin::Arguments* args) {
  base::FilePath file;
  std::vector<base::FilePath> files;
  if (!item.Get("files", &files) && item.Get("file", &file)) {
    files.push_back(file);
  }
  gin::Handle<NativeImage> icon;
  if (!item.Get("icon", &icon) || icon->image().IsEmpty()) {
    gin_helper::ErrorThrower(args->isolate())
        .ThrowError("Must specify non-empty 'icon' option");
    return;
  }
   Start dragging.
  if (!files.empty()) {
    base::CurrentThread::ScopedNestableTaskAllower allow;
    DragFileItems(files, icon->image(), ontents()->GetNativeView());
  } else {
    gin_helper::ErrorThrower(args->isolate())
        .ThrowError("Must specify either 'file' or 'files' option");
  }
}
v8::Local<v8::Promise> WebContents::CapturePage(gin::Arguments* args) {