Implement Vulkan GrBackendObject for textures.

src/gpu/vk/GrVkRenderTarget.h

Index: src/gpu/vk/GrVkRenderTarget.h
diff --git a/src/gpu/vk/GrVkRenderTarget.h b/src/gpu/vk/GrVkRenderTarget.h
index b4d72eac73cf36c4dd9b8d488510a05dc74e26de..21c5788aa15e7aaa3974d522eb9661838cfc9aa0 100644
--- a/src/gpu/vk/GrVkRenderTarget.h
+++ b/src/gpu/vk/GrVkRenderTarget.h
@@ -20,6 +20,8 @@ class GrVkGpu;
 class GrVkImageView;
 class GrVkStencilAttachment;
 
+struct GrVkTextureInfo;
+
 #ifdef SK_BUILD_FOR_WIN
 // Windows gives bogus warnings about inheriting asTexture/asRenderTarget via dominance.
 #pragma warning(push)
@@ -34,7 +36,7 @@ public:
 
     static GrVkRenderTarget* CreateWrappedRenderTarget(GrVkGpu*, const GrSurfaceDesc&,
                                                        GrGpuResource::LifeCycle,
-                                                       const GrVkImage::Resource* resource);
+                                                       const GrVkTextureInfo*);
 
     ~GrVkRenderTarget() override;