### 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.h
void AddObserver(ExtendedWebContentsObserver* obs) {
    observers_.AddObserver(obs);
  }
  void RemoveObserver(ExtendedWebContentsObserver* obs) {
    
    if (observers_.might_have_observers())
      observers_.RemoveObserver(obs);
  }
  bool EmitNavigationEvent(const std::string& event,
                           content::NavigationHandle* navigation_handle);
  
  template <typename... Args>
  bool EmitWithSender(base::StringPiece name,
                      content::RenderFrameHost* sender,
                      electron::mojom::ElectronBrowser::InvokeCallback callback,
                      Args&&... args) {
    DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
    v8::Isolate* isolate = JavascriptEnvironment::GetIsolate();
    v8::HandleScope handle_scope(isolate);
    v8::Local<v8::Object> wrapper;
    if (!GetWrapper(isolate).ToLocal(&wrapper))
      return false;
    v8::Local<v8::Object> event = gin_helper::internal::CreateNativeEvent(
        isolate, wrapper, sender, std::move(callback));
    return EmitCustomEvent(name, event, std::forward<Args>(args)...);
  }
  void MarkDestroyed();
  WebContents* embedder() { return embedder_; }