Dup command-buffer SHM handle before auto-closing.

ppapi/proxy/ppb_context_3d_proxy.cc

 // 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.
 
 #include "ppapi/proxy/ppb_context_3d_proxy.h"
 
 #include "base/hash_tables.h"
 #include "gpu/command_buffer/client/gles2_cmd_helper.h"
 #include "gpu/command_buffer/client/gles2_implementation.h"
 #include "ppapi/c/pp_errors.h"
@@ skipping 115 matching lines @@
 const PPB_Context3D_Dev context_3d_interface = {
   &Create,
   &IsContext3D,
   &GetAttrib,
   &BindSurfaces,
   &GetBoundSurfaces,
 };
 
 base::SharedMemoryHandle SHMHandleFromInt(int shm_handle) {
 #if defined(OS_POSIX)
-  return base::FileDescriptor(shm_handle, true);
+  // The handle isn't ours to close, but we want to keep a reference to the
+  // handle until it is actually sent, so duplicate it, and mark auto-close.
+  return base::FileDescriptor(dup(shm_handle), true);
 #elif defined(OS_WIN)
+  // TODO(piman): DuplicateHandle to the plugin process.
   return reinterpret_cast<HANDLE>(shm_handle);
 #else
 #error "Platform not supported."
 #endif
 }
 
 gpu::CommandBuffer::State GPUStateFromPPState(
     const PP_Context3DTrustedState& s) {
   gpu::CommandBuffer::State state;
   state.num_entries = s.num_entries;
@@ skipping 436 matching lines @@
                                                    &shm_handle,
                                                    &shm_size)) {
     return;
   }
   *transfer_buffer = SHMHandleFromInt(shm_handle);
   *size = shm_size;
 }
 
 }  // namespace proxy
 }  // namespace pp