* Output of `node_modules/.bin/electron --version`: 2.0.0
* Operating System (Platform and Version): Windows 10

**Expected Behavior**
When I disable a window twice via `setEnabled(false)`, I expect the second disable to have no effect.

**Actual behavior**
The second disable is "queued" up, such that I am forced to enable the window twice to get back to normal.

**To Reproduce**
In the electronquickstart repo, in main.js' `createWindow()`, add these lines:

    mainWindow.setEnabled(false);
    mainWindow.setEnabled(false);
    mainWindow.setEnabled(true);

The window will be disabled when launched. 

You see the same issue if you do it in reverse:

    mainWindow.setEnabled(true);
    mainWindow.setEnabled(false); // this doesn't actually disable it, because the window was enabled from the getgo

If this is expected behavior, can the [docs](https://github.com/electron/electron/blob/master/docs/api/browser-window.md#winsetenabledenable) be updated to explain this behavior.
atom/browser/native_window_views.cc
const gfx::Rect& bounds) const {
  if (!has_frame())
    return bounds;
  gfx::Rect content_bounds(bounds);
#if defined(OS_WIN)
  HWND hwnd = GetAcceleratedWidget();
  content_bounds.set_size(
      display::win::ScreenWin::DIPToScreenSize(hwnd, content_bounds.size()));
  RECT rect;
  SetRectEmpty(&rect);
  DWORD style = ::GetWindowLong(hwnd, GWL_STYLE);
  DWORD ex_style = ::GetWindowLong(hwnd, GWL_EXSTYLE);
  AdjustWindowRectEx(&rect, style, FALSE, ex_style);
  content_bounds.set_width(content_bounds.width() - (rect.right - rect.left));
  content_bounds.set_height(content_bounds.height() - (rect.bottom - rect.top));
  content_bounds.set_size(
      display::win::ScreenWin::ScreenToDIPSize(hwnd, content_bounds.size()));
#endif
  if (root_view_->HasMenu() && root_view_->IsMenuBarVisible()) {
    int menu_bar_height = root_view_->GetMenuBarHeight();
    content_bounds.set_y(content_bounds.y() + menu_bar_height);
    content_bounds.set_height(content_bounds.height() - menu_bar_height);
  }
  return content_bounds;
}
void NativeWindowViews::UpdateDraggableRegions(