Add TransferBufferInterface::shared_memory_handle()

gpu/command_buffer/client/transfer_buffer.cc

 // Copyright (c) 2012 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.
 
 // A class to Manage a growing transfer buffer.
 
 #include "gpu/command_buffer/client/transfer_buffer.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/bits.h"
 #include "base/logging.h"
+#include "base/memory/shared_memory_handle.h"
 #include "base/trace_event/trace_event.h"
 #include "gpu/command_buffer/client/cmd_buffer_helper.h"
 
 namespace gpu {
 
 TransferBuffer::TransferBuffer(
     CommandBufferHelper* helper)
     : helper_(helper),
       result_size_(0),
       default_buffer_size_(0),
       min_buffer_size_(0),
       max_buffer_size_(0),
       alignment_(0),
       size_to_flush_(0),
       bytes_since_last_flush_(0),
       buffer_id_(-1),
       result_buffer_(NULL),
       result_shm_offset_(0),
       usable_(true) {
 }
 
 TransferBuffer::~TransferBuffer() {
   Free();
 }
 
+base::SharedMemoryHandle TransferBuffer::shared_memory_handle() const {
+  if (!HaveBuffer())
+    return base::SharedMemoryHandle();
+  if (!buffer_->backing())
+    return base::SharedMemoryHandle();
+  return buffer_->backing()->shared_memory_handle();
+}
+
 bool TransferBuffer::Initialize(
     unsigned int default_buffer_size,
     unsigned int result_size,
     unsigned int min_buffer_size,
     unsigned int max_buffer_size,
     unsigned int alignment,
     unsigned int size_to_flush) {
   result_size_ = result_size;
   default_buffer_size_ = default_buffer_size;
   min_buffer_size_ = min_buffer_size;
@@ skipping 166 matching lines @@
   Release();
   // NOTE: we allocate buffers of size 0 so that HaveBuffer will be true, so
   // that address will return a pointer just like malloc, and so that GetShmId
   // will be valid. That has the side effect that we'll insert a token on free.
   // We could add code skip the token for a zero size buffer but it doesn't seem
   // worth the complication.
   buffer_ = transfer_buffer_->AllocUpTo(new_size, &size_);
 }
 
 }  // namespace gpu