Mac: Clean up visibility state tracking

content/browser/renderer_host/render_widget_host_view_mac.mm

Index: content/browser/renderer_host/render_widget_host_view_mac.mm
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.mm b/content/browser/renderer_host/render_widget_host_view_mac.mm
index 072bc66ab821e03b850cd8a13c084b683100b51b..37802c9acb71680b0ae02d200d28403d55b43d9e 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -408,10 +408,6 @@ float FlipYFromRectToScreen(float y, float rect_height) {
   return cocoa_view_;
 }
 
-bool RenderWidgetHostViewMac::BrowserCompositorMacIsVisible() const {
-  return !render_widget_host_->is_hidden();
-}
-
 SkColor RenderWidgetHostViewMac::BrowserCompositorMacGetGutterColor(
     SkColor color) const {
   // When making an element on the page fullscreen the element's background
@@ -1305,14 +1301,6 @@ float FlipYFromRectToScreen(float y, float rect_height) {
   page_at_minimum_scale_ =
       frame.metadata.page_scale_factor == frame.metadata.min_page_scale_factor;
   if (frame.delegated_frame_data) {
-    // TODO(ccameron): This would not be needed if BrowserCompostiorMac were to
-    // correctly subscribe to the show and hide notifications for
-    // RenderWidgetHostImpl. We do not correctly subscribe to these
-    // notifications because we want to set the hide property property only
-    // after all notifications (the thumbnailer in particular) have all
-    // completed.
-    browser_compositor_->SetRenderWidgetHostIsHidden(
-        render_widget_host_->is_hidden());
     browser_compositor_->SwapCompositorFrame(output_surface_id,
                                              std::move(frame));
     SendVSyncParametersToRenderer();