Allow vulkan to upload data to testing textures with optimal layouts

src/gpu/vk/GrVkImage.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 "GrVkGpu.h"
 #include "GrVkImage.h"
 #include "GrVkMemory.h"
@@ skipping 26 matching lines @@
     if (newLayout == currentLayout) {
         return;
     }
 
     VkAccessFlags srcAccessMask = GrVkMemory::LayoutToSrcAccessMask(currentLayout);
     VkPipelineStageFlags srcStageMask = GrVkMemory::LayoutToPipelineStageFlags(currentLayout);
 
     VkImageAspectFlags aspectFlags = vk_format_to_aspect_flags(fInfo.fFormat);
     VkImageMemoryBarrier imageMemoryBarrier = {
         VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER,          // sType
-        NULL,                                            // pNext
+        nullptr,                                         // pNext
         srcAccessMask,                                   // outputMask
         dstAccessMask,                                   // inputMask
         currentLayout,                                   // oldLayout
         newLayout,                                       // newLayout
         VK_QUEUE_FAMILY_IGNORED,                         // srcQueueFamilyIndex
         VK_QUEUE_FAMILY_IGNORED,                         // dstQueueFamilyIndex
         fInfo.fImage,                                    // image
         { aspectFlags, 0, fInfo.fLevelCount, 0, 1 }      // subresourceRange
     };
 
@@ skipping 91 matching lines @@
 }
 
 void GrVkImage::Resource::freeGPUData(const GrVkGpu* gpu) const {
     VK_CALL(gpu, DestroyImage(gpu->device(), fImage, nullptr));
     bool isLinear = (VK_IMAGE_TILING_LINEAR == fImageTiling);
     GrVkMemory::FreeImageMemory(gpu, isLinear, fAlloc);
 }
 
 void GrVkImage::BorrowedResource::freeGPUData(const GrVkGpu* gpu) const {
 }