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

gpu/command_buffer/service/gpu_scheduler.h

Index: gpu/command_buffer/service/gpu_scheduler.h
===================================================================
--- gpu/command_buffer/service/gpu_scheduler.h	(revision 94701)
+++ gpu/command_buffer/service/gpu_scheduler.h	(working copy)
@@ -15,6 +15,7 @@
 #include "base/shared_memory.h"
 #include "base/task.h"
 #include "gpu/command_buffer/common/command_buffer.h"
+#include "gpu/command_buffer/common/constants.h"
 #include "gpu/command_buffer/service/cmd_buffer_engine.h"
 #include "gpu/command_buffer/service/cmd_parser.h"
 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"
@@ -75,6 +76,11 @@
   void Destroy();
   void DestroyCommon();
 
+  bool MapExternalResource(resource_type::ResourceType resource_type,
+                           uint32 resource_source_id,
+                           GpuScheduler* source_scheduler,
+                           uint32 resource_dest_id);
+
   bool SetParent(GpuScheduler* parent_scheduler, uint32 parent_texture_id);
 
   void PutChanged();