make base::SharedMemoryHandle a class on POSIX.

components/exo/wayland/clients/client_base.cc

Index: components/exo/wayland/clients/client_base.cc
diff --git a/components/exo/wayland/clients/client_base.cc b/components/exo/wayland/clients/client_base.cc
index 8c17ba56ed51b15fbaa3d47db39a00aed4b0b794..e604367854df7083a2fc12f0ae05ffcbeed2a4da 100644
--- a/components/exo/wayland/clients/client_base.cc
+++ b/components/exo/wayland/clients/client_base.cc
@@ -450,9 +450,9 @@ std::unique_ptr<ClientBase::Buffer> ClientBase::CreateBuffer(
   size_t stride = width_ * kBytesPerPixel;
   buffer->shared_memory.reset(new base::SharedMemory());
   buffer->shared_memory->CreateAndMapAnonymous(stride * height_);
-  buffer->shm_pool.reset(
-      wl_shm_create_pool(globals_.shm.get(), buffer->shared_memory->handle().fd,
-                         buffer->shared_memory->requested_size()));
+  buffer->shm_pool.reset(wl_shm_create_pool(
+      globals_.shm.get(), buffer->shared_memory->handle().GetHandle(),
+      buffer->shared_memory->requested_size()));
 
   buffer->buffer.reset(static_cast<wl_buffer*>(wl_shm_pool_create_buffer(
       buffer->shm_pool.get(), 0, width_, height_, stride, kShmFormat)));