Add glBlendBarrierKHR to Skia's GL bindings.

gpu/skia_bindings/gl_bindings_skia_cmd_buffer.cc

Index: gpu/skia_bindings/gl_bindings_skia_cmd_buffer.cc
diff --git a/gpu/skia_bindings/gl_bindings_skia_cmd_buffer.cc b/gpu/skia_bindings/gl_bindings_skia_cmd_buffer.cc
index c40eedb19e3e80b069af778dce2a183dda57217f..021afabe87e104bcf2b7ba31cc74688ff1b4db02 100644
--- a/gpu/skia_bindings/gl_bindings_skia_cmd_buffer.cc
+++ b/gpu/skia_bindings/gl_bindings_skia_cmd_buffer.cc
@@ -30,6 +30,7 @@ GrGLInterface* CreateCommandBufferSkiaGLBinding() {
   functions->fBindTexture = glBindTexture;
   functions->fBindVertexArray = glBindVertexArrayOES;
   functions->fBlendEquation = glBlendEquation;
+  functions->fBlendBarrier = glBlendBarrierKHR;
   functions->fBlendColor = glBlendColor;
   functions->fBlendFunc = glBlendFunc;
   functions->fBufferData = glBufferData;