Allow the renderer process to map textures from one context into another.

gpu/command_buffer/service/gles2_cmd_decoder.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 file contains the GLES2Decoder class.
 
 #ifndef GPU_COMMAND_BUFFER_SERVICE_GLES2_CMD_DECODER_H_
 #define GPU_COMMAND_BUFFER_SERVICE_GLES2_CMD_DECODER_H_
 
 #include <vector>
 
 #include "base/callback.h"
 #include "base/callback_old.h"
 #include "build/build_config.h"
+#include "gpu/command_buffer/common/constants.h"
 #include "gpu/command_buffer/service/common_decoder.h"
 #include "ui/gfx/size.h"
 
 namespace gfx {
 class GLContext;
 class GLSurface;
 }
 
 namespace gpu {
 
@@ skipping 45 matching lines @@
   virtual bool Initialize(const scoped_refptr<gfx::GLSurface>& surface,
                           const scoped_refptr<gfx::GLContext>& context,
                           const gfx::Size& size,
                           const DisallowedExtensions& disallowed_extensions,
                           const char* allowed_extensions,
                           const std::vector<int32>& attribs) = 0;
 
   // Destroys the graphics context.
   virtual void Destroy() = 0;
 
+  // Map a resource from an external context into this context. The source
+  // context need not be in the same share group from the client's point of
+  // view, allowing safe sharing between an "untrusted" context, like Pepper
+  // and a compositor context.
+  //
+  // Currently only texture resources are supported. TODO(apatrick): generalize
+  // this as appropriate.
+  //
+  // To unmap a previously mapped external resource, delete it in the
+  // destination context group. This will not delete the underlying texture
+  // object, just disassociate it with the id in the destination context group.
+  //
+  // The lifetime of the external resource is managed by the context group it
+  // was originally created in. When the last context in that group is destroyed
+  // the resource becomes invalid in all other context groups it is mapped into.
+  virtual bool MapExternalResource(resource_type::ResourceType resource_type,
+                                   uint32 resource_source_id,
+                                   GLES2Decoder* source_decoder,
+                                   uint32 resource_dest_id) = 0;
+
   virtual bool SetParent(GLES2Decoder* parent_decoder,
                          uint32 parent_texture_id) = 0;
 
   // Resize an offscreen frame buffer.
   virtual void ResizeOffscreenFrameBuffer(const gfx::Size& size) = 0;
 
   // Force the offscreen frame buffer's size to be updated. This
   // usually occurs lazily, during SwapBuffers, but on some platforms
   // (Mac OS X in particular) it must be done immediately.
   virtual bool UpdateOffscreenFrameBufferSize() = 0;
@@ skipping 34 matching lines @@
  private:
   bool debug_;
 
   DISALLOW_COPY_AND_ASSIGN(GLES2Decoder);
 };
 
 }  // namespace gles2
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_SERVICE_GLES2_CMD_DECODER_H_