Allow GLSurface to indicate that it supports a specific extension.

ui/gfx/gl/gl_surface.h

 // Copyright (c) 2011 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_GFX_GL_GL_SURFACE_H_
 #define UI_GFX_GL_GL_SURFACE_H_
 #pragma once
 
 #include "base/memory/ref_counted.h"
 #include "build/build_config.h"
@@ skipping 28 matching lines @@
   // Swaps front and back buffers. This has no effect for off-screen
   // contexts.
   virtual bool SwapBuffers() = 0;
 
   // Get the size of the surface.
   virtual gfx::Size GetSize() = 0;
 
   // Get the underlying platform specific surface "handle".
   virtual void* GetHandle() = 0;
 
+  // Returns space separated list of surface specific extensions.
+  // The surface must be current.
+  virtual std::string GetExtensions();
+
   // Returns the internal frame buffer object name if the surface is backed by
   // FBO. Otherwise returns 0.
   virtual unsigned int GetBackingFrameBufferObject();
 
   // Copy part of the backbuffer to the frontbuffer.
-  virtual bool SupportsPostSubBuffer();
   virtual bool PostSubBuffer(int x, int y, int width, int height);
 
   static bool InitializeOneOff();
 
   // Called after a context is made current with this surface. Returns false
   // on error.
   virtual bool OnMakeCurrent(GLContext* context);
 
   // This gives a hint as to whether this surface is visible. If it is not
   // visible, the backing store need not be preserved.
@@ skipping 60 matching lines @@
   GLSurface* surface() const { return surface_.get(); }
 
  private:
   scoped_refptr<GLSurface> surface_;
   DISALLOW_COPY_AND_ASSIGN(GLSurfaceAdapter);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_GL_GL_SURFACE_H_