Refactor vulkan buffer mapping and unmapping

src/gpu/vk/GrVkGpu.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 "GrContextOptions.h"
@@ skipping 583 matching lines @@
         region.imageSubresource = { VK_IMAGE_ASPECT_COLOR_BIT, SkToU32(currentMipLevel), 0, 1 };
         region.imageOffset = { left, flipY ? tex->height() - top - currentHeight : top, 0 };
         region.imageExtent = { (uint32_t)currentWidth, (uint32_t)currentHeight, 1 };
 
         currentWidth = SkTMax(1, currentWidth/2);
         currentHeight = SkTMax(1, currentHeight/2);
     }
 
     transferBuffer->unmap();
 
-    // make sure the unmap has finished
-    transferBuffer->addMemoryBarrier(this,
-                                     VK_ACCESS_HOST_WRITE_BIT,
-                                     VK_ACCESS_TRANSFER_READ_BIT,
-                                     VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT,
-                                     VK_PIPELINE_STAGE_TRANSFER_BIT,
-                                     false);
-
     // Change layout of our target so it can be copied to
     tex->setImageLayout(this,
                         VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL,
                         VK_ACCESS_TRANSFER_WRITE_BIT,
                         VK_PIPELINE_STAGE_TRANSFER_BIT,
                         false);
 
     // Copy the buffer to the image
     fCurrentCmdBuffer->copyBufferToImage(this,
                                          transferBuffer,
@@ skipping 1227 matching lines @@
     // Currently it is fine for us to always pass in 1 for the clear count even if no attachment
     // uses it. In the current state, we also only use the LOAD_OP_CLEAR for the color attachment
     // which is always at the first attachment.
     fCurrentCmdBuffer->beginRenderPass(this, renderPass, 1, colorClear, *target, *pBounds, true);
     fCurrentCmdBuffer->executeCommands(this, buffer);
     fCurrentCmdBuffer->endRenderPass(this);
 
     this->didWriteToSurface(target, &bounds);
 }