message: Adds more useful debug information to an error message when no kernels are found.
diff: @@ -369,7 +369,8 @@ class ColocationGraph {
  "Could not satisfy explicit device specification '",
  node->requested_device(), "' because no supported kernel for ",
  specified_device_name.type, " devices is available.",
  - debug_info);
  + debug_info, "\nRegistered kernels:\n",
  + KernelsRegisteredForOp(node->type_string()));
  } else {
  return errors::InvalidArgument(
  "Could not satisfy explicit device specification '",
  