- Electron version: 1.2.8
- Operating system: Windows

Hi,

I've been trying to get a context menu containing some [predefined web contents roles](https://github.com/electron/electron/blob/master/lib/browser/api/menu-item-roles.js#L17) working for an application where we have multiple windows simultaneously. I've noticed that when a context menu is opened for a window that was created later than others, the role commands don't seem to execute when clicked. However, if don't use a role and instead define a click handler that calls the command on the web contents manually, it behaves normally.

I've been doing some digging and it seems that the reason is because, for a role, [`electron.webContents.getFocusedWebContents`](https://github.com/electron/electron/blob/master/lib/browser/api/web-contents.js#L257) is used to determine which web contents to call the command on (see [menu.js](https://github.com/electron/electron/blob/master/lib/browser/api/menu.js#L121)).

This function iterates through all existing web contents, then returns the first in the collection that is in a `webview`, otherwise the first that returns `true` from `contents.isFocused()`. However, it seems to be entirely possible that there are web contents other than the one that the context menu was raised for, who think they are focused (or perhaps are within a `webview`), and who were created earlier and therefore appear earlier in the collection.

This means there are situations when the 'wrong' web contents is returned from `getFocusedWebContents`, and therefore the role command is called on that 'wrong' web contents, which leads to the unexpected behaviour described above.

Is this a bug? And if so, is there a fix and/or workaround for this? I'm happy to contribute a PR if needed.

atom/browser/api/atom_api_web_contents.cc
if (managed_web_contents()) {
    
    
    if (type_ == WEB_VIEW)
      guest_delegate_->Destroy();
    
    
    
    RenderViewDeleted(web_contents()->GetRenderViewHost());
    WebContentsDestroyed();
  }
}
bool WebContents::AddMessageToConsole(content::WebContents* source,
                                      int32_t level,
                                      const base::string16& message,
                                      int32_t line_no,
                                      const base::string16& source_id) {
  if (type_ == BROWSER_WINDOW || type_ == OFF_SCREEN) {
    return false;
  } else {
    Emit("console-message", level, message, line_no, source_id);
    return true;
  }
}
void WebContents::OnCreateWindow(const GURL& target_url,