Add fence support for TransferBuffers

src/gpu/gl/GrGLInterface.cpp

Index: src/gpu/gl/GrGLInterface.cpp
diff --git a/src/gpu/gl/GrGLInterface.cpp b/src/gpu/gl/GrGLInterface.cpp
index c3fc8a8e8138db14d900f237edf22072d1233ef5..0a157dda11111a53e41e652da0b5cd92b92a379d 100644
--- a/src/gpu/gl/GrGLInterface.cpp
+++ b/src/gpu/gl/GrGLInterface.cpp
@@ -786,6 +786,24 @@ bool GrGLInterface::validate() const {
         }
     }
 
+    if (kGL_GrGLStandard == fStandard) {
+        if (glVer >= GR_GL_VER(3, 2) || fExtensions.has("GL_ARB_sync")) {
+            if (nullptr == fFunctions.fFenceSync ||
+                nullptr == fFunctions.fClientWaitSync ||
+                nullptr == fFunctions.fDeleteSync) {
+                RETURN_FALSE_INTERFACE
+            }
+        }
+    } else if (kGLES_GrGLStandard == fStandard) {
+        if (glVer >= GR_GL_VER(3, 0)) {
+            if (nullptr == fFunctions.fFenceSync ||
+                nullptr == fFunctions.fClientWaitSync ||
+                nullptr == fFunctions.fDeleteSync) {
+                RETURN_FALSE_INTERFACE
+            }
+        }
+    }
+
     if (fExtensions.has("EGL_KHR_image") || fExtensions.has("EGL_KHR_image_base")) {
         if (nullptr == fFunctions.fEGLCreateImage ||
             nullptr == fFunctions.fEGLDestroyImage) {