gpu: Add support for GLX_EXT_texture_from_pixmap extension.

ui/gl/gl_surface_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_SURFACE_GLX_H_
 #define UI_GL_GL_SURFACE_GLX_H_
 #pragma once
 
 #include "base/compiler_specific.h"
 #include "ui/base/x/x11_util.h"
@@ skipping 79 matching lines @@
   virtual ~PbufferGLSurfaceGLX();
 
  private:
   gfx::Size size_;
   void* config_;
   XID pbuffer_;
 
   DISALLOW_COPY_AND_ASSIGN(PbufferGLSurfaceGLX);
 };
 
+// A surface used to render to an offscreen pixmap.
+class GL_EXPORT PixmapGLSurfaceGLX : public GLSurfaceGLX {

[piman, 2012/06/12 23:15:38]

Do you really need to make this structure a GLSurface? The concept of a
GLSurface is only used to make contexts current on them. In this case you're
only using it to bind to a texture, so there's a bunch of stuff that doesn't
apply (SwapBuffers) and/or is coerced into wrong types
(GetHandle/GetConfig/...). It sounds like for the purpose of this CL you could
make a simpler class without all that baggage.

+ public:
+  explicit PixmapGLSurfaceGLX(XID pixmap);
+
+  // Implement GLSurfaceGLX.
+  virtual bool Initialize() OVERRIDE;
+  virtual void Destroy() OVERRIDE;
+  virtual bool IsOffscreen() OVERRIDE;
+  virtual bool SwapBuffers() OVERRIDE;
+  virtual gfx::Size GetSize() OVERRIDE;
+  virtual void* GetHandle() OVERRIDE;
+  virtual void* GetConfig() OVERRIDE;
+  virtual void* GetShareHandle() OVERRIDE;
+
+ protected:
+  virtual ~PixmapGLSurfaceGLX();
+
+ private:
+  void* config_;
+  XID pixmap_;
+  XID glx_pixmap_;
+  gfx::Size size_;
+
+  DISALLOW_COPY_AND_ASSIGN(PixmapGLSurfaceGLX);
+};
+
 }  // namespace gfx
 
 #endif  // UI_GL_GL_SURFACE_GLX_H_