Add gpu::BufferBacking::shared_memory_handle()

gpu/command_buffer/common/buffer.cc

Index: gpu/command_buffer/common/buffer.cc
diff --git a/gpu/command_buffer/common/buffer.cc b/gpu/command_buffer/common/buffer.cc
index 13b606c3286734c4ad04723fd5248239b27143f1..c8d6bbc6045206095202bc2172ced5b38e2de9c9 100644
--- a/gpu/command_buffer/common/buffer.cc
+++ b/gpu/command_buffer/common/buffer.cc
@@ -18,6 +18,10 @@ bool BufferBacking::is_shared() const {
   return false;
 }
 
+base::SharedMemoryHandle BufferBacking::shared_memory_handle() const {
+  return base::SharedMemoryHandle();
+}
+
 SharedMemoryBufferBacking::SharedMemoryBufferBacking(
     std::unique_ptr<base::SharedMemory> shared_memory,
     size_t size)
@@ -29,6 +33,11 @@ bool SharedMemoryBufferBacking::is_shared() const {
   return true;
 }
 
+base::SharedMemoryHandle SharedMemoryBufferBacking::shared_memory_handle()
+    const {
+  return shared_memory_->handle();
+}
+
 void* SharedMemoryBufferBacking::GetMemory() const {
   return shared_memory_->memory();
 }