Add fence support for TransferBuffers

include/gpu/GrCaps.h

Index: include/gpu/GrCaps.h
diff --git a/include/gpu/GrCaps.h b/include/gpu/GrCaps.h
index b7c91c48135992f0c5b937e81a77f34e65f9b6fd..a97be72c3ff52c31d75f65f5856b5ae6127c5a98 100644
--- a/include/gpu/GrCaps.h
+++ b/include/gpu/GrCaps.h
@@ -286,6 +286,8 @@ public:
 
     bool sampleShadingSupport() const { return fSampleShadingSupport; }
 
+    bool fenceSyncSupport() const { return fFenceSyncSupport; }
+
 protected:
     /** Subclasses must call this at the end of their constructors in order to apply caps
         overrides requested by the client. Note that overrides will only reduce the caps never
@@ -324,6 +326,8 @@ protected:
     bool fPreferVRAMUseOverFlushes                   : 1;
 
     bool fSampleShadingSupport                       : 1;
+    // TODO: this may need to be an enum to support different fence types
+    bool fFenceSyncSupport                           : 1;
 
     InstancedSupport fInstancedSupport;