Add fence support for TransferBuffers

src/gpu/gl/GrGLAssembleInterface.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "gl/GrGLAssembleInterface.h"
 #include "GrGLUtil.h"
@@ skipping 504 matching lines @@
 
     if (extensions.has("GL_EXT_window_rectangles")) {
         GET_PROC_SUFFIX(WindowRectangles, EXT);
     }
 
     if (extensions.has("EGL_KHR_image") || extensions.has("EGL_KHR_image_base")) {
         GET_EGL_PROC_SUFFIX(CreateImage, KHR);
         GET_EGL_PROC_SUFFIX(DestroyImage, KHR);
     }
 
-    if (glVer >= GR_GL_VER(4,0) || extensions.has("GL_ARB_sample_shading")) {
+    if (glVer >= GR_GL_VER(4, 0) || extensions.has("GL_ARB_sample_shading")) {
         GET_PROC(MinSampleShading);
     }
 
+    if (glVer >= GR_GL_VER(3, 2) || extensions.has("GL_ARB_sync")) {
+        GET_PROC(FenceSync);
+        GET_PROC(ClientWaitSync);
+        GET_PROC(DeleteSync);
+    }
+
     interface->fStandard = kGL_GrGLStandard;
     interface->fExtensions.swap(&extensions);
 
     return interface;
 }
 
 const GrGLInterface* GrGLAssembleGLESInterface(void* ctx, GrGLGetProc get) {
     GET_PROC_LOCAL(GetString);
     if (nullptr == GetString) {
         return nullptr;
@@ skipping 373 matching lines @@
 
     if (extensions.has("EGL_KHR_image") || extensions.has("EGL_KHR_image_base")) {
         GET_EGL_PROC_SUFFIX(CreateImage, KHR);
         GET_EGL_PROC_SUFFIX(DestroyImage, KHR);
     }
 
     if (extensions.has("GL_OES_sample_shading")) {
         GET_PROC_SUFFIX(MinSampleShading, OES);
     }
 
+    if (version >= GR_GL_VER(3, 0)) {
+        GET_PROC(FenceSync);
+        GET_PROC(ClientWaitSync);
+        GET_PROC(DeleteSync);
+    }
+
     interface->fStandard = kGLES_GrGLStandard;
     interface->fExtensions.swap(&extensions);
 
     return interface;
 }