Add TransferBufferInterface::shared_memory_handle()

gpu/command_buffer/client/transfer_buffer.cc

Index: gpu/command_buffer/client/transfer_buffer.cc
diff --git a/gpu/command_buffer/client/transfer_buffer.cc b/gpu/command_buffer/client/transfer_buffer.cc
index 161c836c3ae87b3c88d754a045cef24f8bb2e8ee..0aa21049e556005ab325eb854321c7a6ef04985e 100644
--- a/gpu/command_buffer/client/transfer_buffer.cc
+++ b/gpu/command_buffer/client/transfer_buffer.cc
@@ -11,6 +11,7 @@
 
 #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"
 
@@ -36,6 +37,14 @@ 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,