Get real GPU memory values on NV+Linux and OS X

ui/gl/gl_context_glx.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 UI_GL_GL_CONTEXT_GLX_H_
 #define UI_GL_GL_CONTEXT_GLX_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
@@ skipping 15 matching lines @@
   // Implement GLContext.
   virtual bool Initialize(
       GLSurface* compatible_surface, GpuPreference gpu_preference) OVERRIDE;
   virtual void Destroy() OVERRIDE;
   virtual bool MakeCurrent(GLSurface* surface) OVERRIDE;
   virtual void ReleaseCurrent(GLSurface* surface) OVERRIDE;
   virtual bool IsCurrent(GLSurface* surface) OVERRIDE;
   virtual void* GetHandle() OVERRIDE;
   virtual void SetSwapInterval(int interval) OVERRIDE;
   virtual std::string GetExtensions() OVERRIDE;
+  virtual bool GetTotalGpuMemory(size_t* bytes) OVERRIDE;
   virtual bool WasAllocatedUsingRobustnessExtension() OVERRIDE;
 
  protected:
   virtual ~GLContextGLX();
 
  private:
   void* context_;
   Display* display_;
 
   DISALLOW_COPY_AND_ASSIGN(GLContextGLX);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_GL_CONTEXT_GLX_H_