ResourceScheduler get visual signal from RenderViewHostImpl

content/browser/renderer_host/render_widget_host_impl.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_
 
 #include <deque>
 #include <list>
 #include <map>
@@ skipping 189 matching lines @@
   virtual void Shutdown();
 
   // IPC::Listener
   virtual bool OnMessageReceived(const IPC::Message& msg) OVERRIDE;
 
   // Sends a message to the corresponding object in the renderer.
   virtual bool Send(IPC::Message* msg) OVERRIDE;
 
   // 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_; }
 
   // Called to notify the RenderWidget that its associated native window
   // got/lost focused.
   virtual void GotFocus();
   virtual void LostCapture();
 
   // Called to notify the RenderWidget that it has lost the mouse lock.
@@ skipping 623 matching lines @@
   typedef std::map<int,
       base::Callback<void(const unsigned char*, size_t)> > PendingSnapshotMap;
   PendingSnapshotMap pending_browser_snapshots_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_