Add fence support for TransferBuffers

src/gpu/GrGpu.cpp

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "GrGpu.h"
 
@@ skipping 384 matching lines @@
     mipLevel.fRowBytes = rowBytes;
     SkSTArray<1, GrMipLevel> texels;
     texels.push_back(mipLevel);
 
     return this->writePixels(surface, left, top, width, height, config, texels);
 }
 
 bool GrGpu::transferPixels(GrSurface* surface,
                            int left, int top, int width, int height,
                            GrPixelConfig config, GrBuffer* transferBuffer,
-                           size_t offset, size_t rowBytes) {
+                           size_t offset, size_t rowBytes, GrFence* fence) {
     SkASSERT(transferBuffer);
+    SkASSERT(fence);
 
     this->handleDirtyContext();
     if (this->onTransferPixels(surface, left, top, width, height, config,
                                transferBuffer, offset, rowBytes)) {
         SkIRect rect = SkIRect::MakeXYWH(left, top, width, height);
         this->didWriteToSurface(surface, &rect);
         fStats.incTransfersToTexture();
+
+        if (*fence) {
+            this->deleteFence(*fence);
+        }
+        *fence = this->insertFence();
+
         return true;
     }
     return false;
 }
 
 void GrGpu::resolveRenderTarget(GrRenderTarget* target) {
     SkASSERT(target);
     this->handleDirtyContext();
     this->onResolveRenderTarget(target);
 }
@@ skipping 65 matching lines @@
         // This doesn't have geometric meaning. We just need to define an ordering for std::map.
         if (a[i].x() != b[i].x()) {
             return a[i].x() < b[i].x();
         }
         if (a[i].y() != b[i].y()) {
             return a[i].y() < b[i].y();
         }
     }
     return false; // Equal.
 }