Make sk_app::WindowContext directly create a SkSurface without an intermediate GrRenderTarget
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2165703002

Review-Url: https://codereview.chromium.org/2165703002
diff --git a/tools/viewer/sk_app/VulkanWindowContext.cpp b/tools/viewer/sk_app/VulkanWindowContext.cpp
index 5087e5d..c969f28 100644
--- a/tools/viewer/sk_app/VulkanWindowContext.cpp
+++ b/tools/viewer/sk_app/VulkanWindowContext.cpp
@@ -278,9 +278,8 @@
         desc.fSampleCnt = 0;
         desc.fStencilBits = 0;
         desc.fRenderTargetHandle = (GrBackendObject) &info;
-        fRenderTargets[i].reset(fContext->textureProvider()->wrapBackendRenderTarget(desc));
 
-        fSurfaces[i] = this->createRenderSurface(fRenderTargets[i], 24);
+        fSurfaces[i] = this->createRenderSurface(desc, 24);
     }
 
     // create the command pool for the command buffers