RendererGLContext supports reparenting a GL context.

content/renderer/gpu/renderer_gl_context.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.
 
 // This API is consistent with other OpenGL setup APIs like window's WGL
 // and pepper's PGL. This API is used to manage OpenGL RendererGLContexts in the
 // Chrome renderer process in a way that is consistent with other platforms.
 
 #ifndef CONTENT_RENDERER_GPU_RENDERER_GL_CONTEXT_H_
 #define CONTENT_RENDERER_GPU_RENDERER_GL_CONTEXT_H_
@@ skipping 90 matching lines @@
   // Create a RendererGLContext that renders to an offscreen frame buffer. If
   // parent is not NULL, that RendererGLContext can access a copy of the created
   // RendererGLContext's frame buffer that is updated every time SwapBuffers is
   // called. It is not as general as shared RendererGLContexts in other
   // implementations of OpenGL. If parent is not NULL, it must be used on the
   // same thread as the parent. A child RendererGLContext may not outlive its
   // parent.  attrib_list must be NULL or a NONE-terminated list of
   // attribute/value pairs.
   static RendererGLContext* CreateOffscreenContext(
       GpuChannelHost* channel,
-      RendererGLContext* parent,
       const gfx::Size& size,
       const char* allowed_extensions,
       const int32* attrib_list,
       const GURL& active_url);
 
+  // Sets the parent context. If any parent textures have been created for
+  // another parent, it is important to delete them before changing the parent.
+  bool SetParent(RendererGLContext* parent);
+
   // Resize an offscreen frame buffer. The resize occurs on the next call to
   // SwapBuffers. This is to avoid waiting until all pending GL calls have been
   // executed by the GPU process. Everything rendered up to the call to
   // SwapBuffers will be lost. A lost RendererGLContext will be reported if the
   // resize fails.
   void ResizeOffscreen(const gfx::Size& size);
 
   // For an offscreen frame buffer RendererGLContext, return the texture ID with
   // respect to the parent RendererGLContext. Returns zero if RendererGLContext
   // does not have a parent.
@@ skipping 49 matching lines @@
   // Destroy a latch.
   bool DestroyLatch(uint32 latch);
 
   // All child contexts get a latch pair automatically. These latches are used
   // for synchronization with parent context. If *this* context does not have a
   // parent context, these methods will return false.
   bool GetParentToChildLatch(uint32* parent_to_child_latch);
   bool GetChildToParentLatch(uint32* child_to_parent_latch);
 
  private:
-  RendererGLContext(GpuChannelHost* channel,
-                    RendererGLContext* parent);
+  explicit RendererGLContext(GpuChannelHost* channel);
 
   bool Initialize(bool onscreen,
                   gfx::PluginWindowHandle render_surface,
                   int render_view_id,
                   const gfx::Size& size,
                   const char* allowed_extensions,
                   const int32* attrib_list,
                   const GURL& active_url);
   void Destroy();
 
@@ skipping 13 matching lines @@
   int32 transfer_buffer_id_;
   gpu::gles2::GLES2Implementation* gles2_implementation_;
   gfx::Size size_;
   Error last_error_;
   int frame_number_;
 
   DISALLOW_COPY_AND_ASSIGN(RendererGLContext);
 };
 
 #endif  // CONTENT_RENDERER_GPU_RENDERER_GL_CONTEXT_H_