EGL contexts reference count the EGL surfaces they share....

app/gfx/gl/gl_context_egl.h

 // Copyright (c) 2010 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 APP_GFX_GL_GL_CONTEXT_EGL_H_
 #define APP_GFX_GL_GL_CONTEXT_EGL_H_
 #pragma once
 
+#include "app/gfx/gl/gl_context.h"
+#include "base/ref_counted.h"
 #include "gfx/size.h"
-#include "app/gfx/gl/gl_context.h"
 
 typedef void* EGLDisplay;
 typedef void* EGLContext;
 typedef void* EGLSurface;
 
 namespace gfx {
 
+// Takes ownership of an EGL surface and reference counts it so it can be shared
+// by multiple EGL contexts and destroyed with the last.
+class SharedEGLSurface : public base::RefCounted<SharedEGLSurface> {
+ public:
+  explicit SharedEGLSurface(EGLSurface surface);
+  ~SharedEGLSurface();
+
+  EGLSurface egl_surface() const;
+
+ private:
+  EGLSurface surface_;
+  DISALLOW_COPY_AND_ASSIGN(SharedEGLSurface);
+};
+
 // Interface for EGL contexts. Adds an EGL specific accessor for retreiving
 // the surface.
 class BaseEGLContext : public GLContext {
  public:
   BaseEGLContext() {}
   virtual ~BaseEGLContext() {}
 
   static bool InitializeOneOff();
 
   static EGLDisplay GetDisplay();
 
   // Get the associated EGL surface.
-  virtual EGLSurface GetSurface() = 0;
+  virtual SharedEGLSurface* GetSurface() = 0;
 
   // Implement GLContext.
   virtual std::string GetExtensions();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(BaseEGLContext);
 };
 
 // Encapsulates an EGL OpenGL ES context that renders to a view.
 class NativeViewEGLContext : public BaseEGLContext {
  public:
   explicit NativeViewEGLContext(void* window);
   virtual ~NativeViewEGLContext();
 
   // Initialize an EGL context.
   bool Initialize();
 
   // Implement GLContext.
   virtual void Destroy();
   virtual bool MakeCurrent();
   virtual bool IsCurrent();
   virtual bool IsOffscreen();
   virtual bool SwapBuffers();
   virtual gfx::Size GetSize();
   virtual void* GetHandle();
   virtual void SetSwapInterval(int interval);
 
   // Implement BaseEGLContext.
-  virtual EGLSurface GetSurface();
+  virtual SharedEGLSurface* GetSurface();
 
  private:
   void* window_;
-  EGLSurface surface_;
+  scoped_refptr<SharedEGLSurface> surface_;
   EGLContext context_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeViewEGLContext);
 };
 
 // Encapsulates an EGL OpenGL ES context intended for offscreen use. It is
-// actually associated with a native window and will render to it. The caller
-// must bind an FBO to prevent this. Not using pbuffers because ANGLE does not
-// support them.
+// actually associated with a native window or a pbuffer on supporting platforms
+// and will render to it. The caller must bind an FBO to prevent this.
+// TODO(apatrick): implement pbuffers in ANGLE and change this to
+// PbufferEGLContext and use it on all EGL platforms.
 class SecondaryEGLContext : public BaseEGLContext {
  public:
   SecondaryEGLContext();
   virtual ~SecondaryEGLContext();
 
   // Initialize an EGL context that shares a namespace with another.
   bool Initialize(GLContext* shared_context);
 
   // Implement GLContext.
   virtual void Destroy();
   virtual bool MakeCurrent();
   virtual bool IsCurrent();
   virtual bool IsOffscreen();
   virtual bool SwapBuffers();
   virtual gfx::Size GetSize();
   virtual void* GetHandle();
   virtual void SetSwapInterval(int interval);
 
   // Implement BaseEGLContext.
-  virtual EGLSurface GetSurface();
+  virtual SharedEGLSurface* GetSurface();
 
  private:
-  // All offscreen
-  EGLSurface surface_;
-  bool own_surface_;
+  scoped_refptr<SharedEGLSurface> surface_;
   EGLContext context_;
 
   DISALLOW_COPY_AND_ASSIGN(SecondaryEGLContext);
 };
 
 }  // namespace gfx
 
 #endif  // APP_GFX_GL_GL_CONTEXT_EGL_H_