Fix vulkan build

src/gpu/vk/GrVkUniformBuffer.h

Index: src/gpu/vk/GrVkUniformBuffer.h
diff --git a/src/gpu/vk/GrVkUniformBuffer.h b/src/gpu/vk/GrVkUniformBuffer.h
index d2d9f3230c4c93cfd83f171e5c734edfb464221a..cfde125b3924dd5da2e6ba6e1694f0d08d99ad1f 100644
--- a/src/gpu/vk/GrVkUniformBuffer.h
+++ b/src/gpu/vk/GrVkUniformBuffer.h
@@ -50,10 +50,7 @@ private:
 
     GrVkUniformBuffer(GrVkGpu* gpu, const GrVkBuffer::Desc& desc,
                       const GrVkUniformBuffer::Resource* resource)
-        : INHERITED(desc, resource)
-        , fGpu(gpu) {}
-
-    GrVkGpu* fGpu;
+        : INHERITED(desc, resource) {}
 
     typedef GrVkBuffer INHERITED;
 };