Always add a barrier when old layout was general in vulkan.

src/gpu/vk/GrVkImage.cpp

Index: src/gpu/vk/GrVkImage.cpp
diff --git a/src/gpu/vk/GrVkImage.cpp b/src/gpu/vk/GrVkImage.cpp
index a7fe478c4fcd7414afc4d9e8b236eb3c4d043865..d0457ca28b687b74345b4df0a7c45dee1351ec96 100644
--- a/src/gpu/vk/GrVkImage.cpp
+++ b/src/gpu/vk/GrVkImage.cpp
@@ -32,9 +32,12 @@ void GrVkImage::setImageLayout(const GrVkGpu* gpu, VkImageLayout newLayout,
     SkASSERT(VK_IMAGE_LAYOUT_UNDEFINED != newLayout &&
              VK_IMAGE_LAYOUT_PREINITIALIZED != newLayout);
     VkImageLayout currentLayout = this->currentLayout();
-    // Is this reasonable? Could someone want to keep the same layout but use the masks to force
-    // a barrier on certain things?
-    if (newLayout == currentLayout) {
+
+    // If the old and new layout are the same, there is no reason to put in a barrier since the
+    // operations used for each layout are implicitly synchronized with eachother. The one exception
+    // is if the layout is GENERAL. In this case the image could have been used for any operation so
+    // we must respect the barrier.
+    if (newLayout == currentLayout && VK_IMAGE_LAYOUT_GENERAL != currentLayout) {
         return;
     }