Create free list heap for suballocation

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2029763002

Review-Url: https://codereview.chromium.org/2029763002
diff --git a/tools/viewer/sk_app/VulkanWindowContext.cpp b/tools/viewer/sk_app/VulkanWindowContext.cpp
index 84f0dfb..9bcf6ca 100644
--- a/tools/viewer/sk_app/VulkanWindowContext.cpp
+++ b/tools/viewer/sk_app/VulkanWindowContext.cpp
@@ -265,7 +265,7 @@
         GrBackendRenderTargetDesc desc;
         GrVkImageInfo info;
         info.fImage = fImages[i];
-        info.fAlloc = { VK_NULL_HANDLE, 0 };
+        info.fAlloc = { VK_NULL_HANDLE, 0, 0 };
         info.fImageLayout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
         info.fImageTiling = VK_IMAGE_TILING_OPTIMAL;
         info.fFormat = format;