/usr/include/ is in libgtest-dev 1.6.0-1ubuntu4.
This file is owned by root:root, with mode 0o755.
..
/usr/include/gtest/
/usr/include/gtest/gtest-spi.h
/usr/include/gtest/gtest-message.h
/usr/include/gtest/gtest-typed-test.h
/usr/include/gtest/gtest_prod.h
/usr/include/gtest/gtest.h
/usr/include/gtest/gtest-printers.h
/usr/include/gtest/gtest-param-test.h.pump
/usr/include/gtest/gtest-death-test.h
/usr/include/gtest/gtest-test-part.h
/usr/include/gtest/internal/
/usr/include/gtest/internal/gtest-internal.h
/usr/include/gtest/internal/gtest-type-util.h
/usr/include/gtest/internal/gtest-death-test-internal.h
/usr/include/gtest/internal/gtest-tuple.h.pump
/usr/include/gtest/internal/gtest-param-util-generated.h
/usr/include/gtest/internal/gtest-filepath.h
/usr/include/gtest/internal/gtest-string.h
/usr/include/gtest/internal/gtest-param-util-generated.h.pump
/usr/include/gtest/internal/gtest-type-util.h.pump
/usr/include/gtest/internal/gtest-linked_ptr.h
/usr/include/gtest/internal/gtest-port.h
/usr/include/gtest/internal/gtest-param-util.h
/usr/include/gtest/internal/gtest-tuple.h
/usr/include/gtest/gtest-param-test.h
/usr/include/gtest/gtest_pred_impl.h