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

content/common/gpu/gpu_messages.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.
 
 // Multiply-included message file, hence no include guard here, but see below
 // for a much smaller-than-usual include guard section.
 
 #include <vector>
 #include <string>
 
@@ skipping 84 matching lines @@
   IPC_STRUCT_TRAITS_MEMBER(gl_renderer)
   IPC_STRUCT_TRAITS_MEMBER(gl_extensions)
   IPC_STRUCT_TRAITS_MEMBER(can_lose_context)
 #if defined(OS_WIN)
   IPC_STRUCT_TRAITS_MEMBER(dx_diagnostics)
 #endif
 IPC_STRUCT_TRAITS_END()
 
 IPC_ENUM_TRAITS(content::CauseForGpuLaunch)
 IPC_ENUM_TRAITS(gpu::error::ContextLostReason)
+IPC_ENUM_TRAITS(gpu::resource_type::ResourceType)
 
 //------------------------------------------------------------------------------
 // GPU Messages
 // These are messages from the browser to the GPU process.
 
 // Tells the GPU process to initialize itself. The browser explicitly
 // requests this be done so that we are guaranteed that the channel is set
 // up between the browser and GPU process before doing any work that might
 // potentially crash the GPU process. Detection of the child process
 // exiting abruptly is predicated on having the IPC channel set up.
@@ skipping 196 matching lines @@
 // These are messages between a renderer process to the GPU process relating to
 // a single OpenGL context.
 // Initialize a command buffer with the given number of command entries.
 // Returns the shared memory handle for the command buffer mapped to the
 // calling process.
 IPC_SYNC_MESSAGE_ROUTED2_1(GpuCommandBufferMsg_Initialize,
                            base::SharedMemoryHandle /* ring_buffer */,
                            int32 /* size */,
                            bool /* result */)
 
+
+// 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.
+IPC_MESSAGE_ROUTED4(GpuCommandBufferMsg_MapExternalResource,
+                    gpu::resource_type::ResourceType /* resource_type */,
+                    uint32 /* resource_source_id */,
+                    int32 /* source_route_id */,
+                    uint32 /* resource_dest_id */)
+
 // Sets the parent command buffer. This allows the parent and child to share
 // textures.
 IPC_SYNC_MESSAGE_ROUTED2_1(GpuCommandBufferMsg_SetParent,
                            int32 /* parent_route_id */,
                            uint32 /* parent_texture_id */,
                            bool /* result */)
 
 // Get the current state of the command buffer.
 IPC_SYNC_MESSAGE_ROUTED0_1(GpuCommandBufferMsg_GetState,
                            gpu::CommandBuffer::State /* state */)
@@ skipping 183 matching lines @@
 
 // Confirm decoder has been reset.
 IPC_MESSAGE_ROUTED0(AcceleratedVideoDecoderHostMsg_ResetDone)
 
 // Decoder has faced end of stream marker in the stream.
 IPC_MESSAGE_ROUTED0(AcceleratedVideoDecoderHostMsg_EndOfStream)
 
 // Video decoder has encountered an error.
 IPC_MESSAGE_ROUTED1(AcceleratedVideoDecoderHostMsg_ErrorNotification,
                     uint32) /* Error ID */