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

gpu/command_buffer/tests/gl_manager.cc

Index: gpu/command_buffer/tests/gl_manager.cc
diff --git a/gpu/command_buffer/tests/gl_manager.cc b/gpu/command_buffer/tests/gl_manager.cc
index 3053abd8c6aaa4c24c6ca1c2c1b82ecaf907151b..d72994be70d24c1565039073b2af229062178425 100644
--- a/gpu/command_buffer/tests/gl_manager.cc
+++ b/gpu/command_buffer/tests/gl_manager.cc
@@ -505,6 +505,10 @@ uint64_t GLManager::GetCommandBufferID() const {
   return command_buffer_id_;
 }
 
+int32_t GLManager::GetExtraCommandBufferData() const {
+  return 0;
+}
+
 uint64_t GLManager::GenerateFenceSyncRelease() {
   return next_fence_sync_release_++;
 }