* **Electron Version:**
  4.0.2
* **Operating System:**
  macOS 10.14.3
* **Last Known Working Electron version:**:
  1.7

### Expected Behavior
When creating a BrowserWindow it should not appear in the dock menu by defaults.

### Actual Behavior
It appears in the dock menu (example: `raven` in https://electronjs.org/docs/tutorial/macos-dock)

### To Reproduce
Just create new BrowserWindow, then right click on the app icon in the dock. (see https://electronjs.org/docs/tutorial/macos-dock)

At least it should be a way to control that, this can be achieve for top level window with:
`[window_ setExcludedFromWindowsMenu:YES];`, indeed [window isExcludedFromWindowsMenu] returns false by default, see

https://developer.apple.com/documentation/appkit/nsapplication/1428625-removewindowsitem
`Use the isExcludedFromWindowsMenu method of NSWindow if you want the item to remain excluded from the Window menu.`
https://developer.apple.com/documentation/appkit/nswindow/1419175-isexcludedfromwindowsmenu

atom/browser/native_window_views.cc
size = ContentBoundsToWindowBounds(gfx::Rect(size)).size();
  widget()->CenterWindow(size);
#if defined(OS_WIN)
  
  if (fullscreen)
    last_window_state_ = ui::SHOW_STATE_FULLSCREEN;
  else
    last_window_state_ = ui::SHOW_STATE_NORMAL;
  last_normal_bounds_ = GetBounds();
#endif
#if defined(OS_LINUX)
  
  aura::Window* window = GetNativeWindow();
  if (window)
    window->AddPreTargetHandler(this);
#endif
}
NativeWindowViews::~NativeWindowViews() {
  widget()->RemoveObserver(this);
#if defined(OS_WIN)
  
  SetForwardMouseMessages(false);
#endif
#if defined(OS_LINUX)
  aura::Window* window = GetNativeWindow();
  if (window)
    window->RemovePreTargetHandler(this);
#endif
}
void NativeWindowViews::SetContentView(views::View* view) {