Wait for all device work to finish before destroy VkDevice

src/gpu/vk/GrVkBackendContext.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "vk/GrVkBackendContext.h"
 #include "vk/GrVkExtensions.h"
 #include "vk/GrVkInterface.h"
@@ skipping 220 matching lines @@
     ctx->fQueueFamilyIndex = graphicsQueueIndex;
     ctx->fMinAPIVersion = kGrVkMinimumVersion;
     ctx->fExtensions = extensionFlags;
     ctx->fFeatures = featureFlags;
     ctx->fInterface.reset(GrVkCreateInterface(inst, device, extensionFlags));
 
     return ctx;
 }
 
 GrVkBackendContext::~GrVkBackendContext() {
+    vkDeviceWaitIdle(fDevice);
     vkDestroyDevice(fDevice, nullptr);
     fDevice = VK_NULL_HANDLE;
     vkDestroyInstance(fInstance, nullptr);
     fInstance = VK_NULL_HANDLE;
 }