Added an extra sync token field for extra command buffer identification.

gpu/gles2_conform_support/egl/display.cc

Index: gpu/gles2_conform_support/egl/display.cc
diff --git a/gpu/gles2_conform_support/egl/display.cc b/gpu/gles2_conform_support/egl/display.cc
index b610ced352a068de1cf3e966eaa9f162cc64451d..12488a6543e9d5530f42ade69f161b6596fa35f0 100644
--- a/gpu/gles2_conform_support/egl/display.cc
+++ b/gpu/gles2_conform_support/egl/display.cc
@@ -349,6 +349,10 @@ uint64_t Display::GetCommandBufferID() const {
   return 0;
 }
 
+uint32_t Display::GetExtraCommandBufferData() const {
+  return 0;
+}
+
 uint64_t Display::GenerateFenceSyncRelease() {
   return next_fence_sync_release_++;
 }