Changed the signature of Application::Draw to accept elapsed time. It will be...

gpu/demos/app_framework/application.h

 // Copyright (c) 2006-2009 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.
 
 // Base class for gles2 applications using command buffer.
 
 #ifndef GPU_DEMOS_APP_FRAMEWORK_APPLICATION_H_
 #define GPU_DEMOS_APP_FRAMEWORK_APPLICATION_H_
 
 #include "base/at_exit.h"
 #include "base/message_loop.h"
+#include "base/time.h"
 
 #include "gpu/demos/app_framework/platform.h"
 
 namespace gpu_demos {
 
 // Acts as a base class for GLES2 applications using command buffer.
 // The derived calls needs to call InitRenderContext() to create a render
 // surface and initialize a rendering context. Currently it only creates
 // an on-screen window. It will be extended to support pepper/nacl plugin
 // when pepper 3D api is in place.
 class Application {
  public:
   Application();
   virtual ~Application();
 
   // Enters the event processing loop.
   void MainLoop();
   void OnPaint();
 
  protected:
   // Returns the width of rendering surface.
   inline int width() const { return width_; }
   // Returns the height of rendering surface.
   inline int height() const { return height_; }
 
   bool InitRenderContext();
 
-  virtual void Draw() = 0;
+  // The framework calls this function for the derived classes to do custom
+  // rendering. There is no default implementation. It must be defined by the
+  // derived classes. The elapsed_sec param represents the time elapsed
+  // (in seconds) after Draw was called the last time. It can be used to
+  // make the application frame-rate independent. It is 0.0f for the
+  // first draw call.
+  virtual void Draw(float elapsed_sec) = 0;
 
  private:
   // Creates a native on-screen window.
   NativeWindowHandle CreateNativeWindow();
 
   int width_;
   int height_;
   NativeWindowHandle window_handle_;
 
+  // Time at which draw was called last.
+  base::Time last_draw_time_;
+
   // The following two variables are just needed to satisfy
   // the assumption that we are running inside a browser.
   base::AtExitManager at_exit_manager_;
   MessageLoopForUI message_loop_;
 
   DISALLOW_COPY_AND_ASSIGN(Application);
 };
 
 }  // namespace gpu_demos
 #endif  // GPU_DEMOS_APP_FRAMEWORK_APPLICATION_H_