Add fence support for TransferBuffers

src/gpu/vk/GrVkGpu.h

Index: src/gpu/vk/GrVkGpu.h
diff --git a/src/gpu/vk/GrVkGpu.h b/src/gpu/vk/GrVkGpu.h
index eeaacf3d1b08d407cc08277027b37220923d0998..273f28c5dbfb1978279d24a97479e0359d8ecfd5 100644
--- a/src/gpu/vk/GrVkGpu.h
+++ b/src/gpu/vk/GrVkGpu.h
@@ -141,6 +141,10 @@ public:
 
     void finishDrawTarget() override;
 
+    GrFence SK_WARN_UNUSED_RESULT insertFence() const override;
+    bool waitFence(GrFence, uint64_t timeout) const override;
+    void deleteFence(GrFence) const override;
+
     void generateMipmap(GrVkTexture* tex);
 
     bool updateBuffer(GrVkBuffer* buffer, const void* src, VkDeviceSize offset, VkDeviceSize size);