Support use of non-coherent memory allocations in Vulkan.

src/gpu/vk/GrVkBuffer.cpp

Index: src/gpu/vk/GrVkBuffer.cpp
diff --git a/src/gpu/vk/GrVkBuffer.cpp b/src/gpu/vk/GrVkBuffer.cpp
index a03ea0cc41ef43ba0c4f71b7b4eaa9054409c27f..b16251c14da83afaeaaa63f771e88f7f95aec186 100644
--- a/src/gpu/vk/GrVkBuffer.cpp
+++ b/src/gpu/vk/GrVkBuffer.cpp
@@ -151,6 +151,7 @@ void GrVkBuffer::vkUnmap(GrVkGpu* gpu) {
     SkASSERT(this->vkIsMapped());
 
     if (fDesc.fDynamic) {
+        GrVkMemory::FlushMappedAlloc(gpu, this->alloc());
         VK_CALL(gpu, UnmapMemory(gpu->device(), this->alloc().fMemory));
     } else {
         gpu->updateBuffer(this, fMapPtr, this->offset(), this->size());
@@ -199,6 +200,7 @@ bool GrVkBuffer::vkUpdateData(GrVkGpu* gpu, const void* src, size_t srcSizeInByt
 
     memcpy(mapPtr, src, srcSizeInBytes);
 
+    GrVkMemory::FlushMappedAlloc(gpu, this->alloc());
     VK_CALL(gpu, UnmapMemory(gpu->device(), alloc.fMemory));
 
     return true;