ResourceScheduler get visual signal from RenderViewHostImpl

content/browser/renderer_host/render_widget_host_impl.h

Index: content/browser/renderer_host/render_widget_host_impl.h
diff --git a/content/browser/renderer_host/render_widget_host_impl.h b/content/browser/renderer_host/render_widget_host_impl.h
index a8ec18a148ca7fa3ac4a8994ef085d8e1525fa25..d25b9dd69ae1cf7d95efdb03aff3f3ac0398a263 100644
--- a/content/browser/renderer_host/render_widget_host_impl.h
+++ b/content/browser/renderer_host/render_widget_host_impl.h
@@ -207,8 +207,8 @@ class CONTENT_EXPORT RenderWidgetHostImpl
 
   // Called to notify the RenderWidget that it has been hidden or restored from
   // having been hidden.
-  void WasHidden();
-  void WasShown(const ui::LatencyInfo& latency_info);
+  virtual void WasHidden();
+  virtual void WasShown(const ui::LatencyInfo& latency_info);
 
   // Returns true if the RenderWidget is hidden.
   bool is_hidden() const { return is_hidden_; }