Fix the race condition between mac drawRect and toggling accelerated compositing

content/browser/renderer_host/render_widget_host_view_mac.h

Index: content/browser/renderer_host/render_widget_host_view_mac.h
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.h b/content/browser/renderer_host/render_widget_host_view_mac.h
index 04a0876c875cdbd16d226df74f1ff46ee6ecc06d..099077c731f149528c9dce1c6791fe19fe702a68 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.h
+++ b/content/browser/renderer_host/render_widget_host_view_mac.h
@@ -331,6 +331,9 @@ class RenderWidgetHostViewMac : public RenderWidgetHostView {
   // prevent us from scheduling multiple calls.
   bool call_set_needs_display_in_rect_pending_;
 
+  // Whether last rendered frame was accelerated.
+  bool last_frame_was_accelerated_;
+
   // The invalid rect that needs to be painted by callSetNeedsDisplayInRect.
   // This value is only meaningful when
   // |call_set_needs_display_in_rect_pending_| is true.