Got disabled in chromium 71 upgrade https://github.com/electron/electron/commit/798b2a3ffd55c477af6258f0afb71000c9f8ecde

/cc @brenca @codebytere 
atom/browser/osr/osr_render_widget_host_view.h
@class NSWindow;
#else
class CALayer;
class NSWindow;
#endif
#endif
namespace content {
class CursorManager;
}  
namespace atom {
class AtomCopyFrameGenerator;
class AtomBeginFrameTimer;
#if defined(OS_MACOSX)
class MacHelper;
#endif
class OffScreenRenderWidgetHostView : public content::RenderWidgetHostViewBase,
                                      public ui::CompositorDelegate,
#if !defined(OS_MACOSX)
                                      public content::DelegatedFrameHostClient,
#endif
                                      public OffscreenViewProxyObserver {
 public: