"using namespace" in header files

[Alan Griffiths]

"Do not use a using-directive in a header file. " - https://unity.ubuntu.com/mir/cppguide/index.html?showone=Namespaces#Namespaces

$ find . -name \*.h | xargs grep "using namespace"
./tests/unit-tests/graphics/android/hwc_struct_helpers.h: using namespace testing;
./tests/include/mir/test/doubles/mock_hwc_composer_device_1.h: using namespace testing;
./tests/include/mir/test/doubles/mock_client_context.h: using namespace testing;
./tests/include/mir/test/doubles/mock_buffer.h: using namespace testing;
./tests/include/mir/test/doubles/mock_buffer.h: using namespace testing;
./tests/include/mir/test/doubles/mock_display_buffer.h: using namespace testing;
./tests/include/mir/test/doubles/mock_android_native_buffer.h: using namespace testing;
./tests/include/mir/test/doubles/mock_hwc_device_wrapper.h: using namespace testing;
./tests/include/mir/test/doubles/stub_display_builder.h: using namespace testing;
./tests/include/mir/test/doubles/mock_platform_ipc_operations.h: using namespace testing;
./tests/include/mir/test/doubles/mock_frontend_surface.h: using namespace testing;
./tests/include/mir/test/doubles/mock_android_alloc_device.h: using namespace testing;
./tests/include/mir/test/doubles/mock_window_handle_repository.h: using namespace testing;
./tests/include/mir_test_framework/testing_server_configuration.h:using namespace mir;
./tests/include/mir_test_framework/stubbed_server_configuration.h:using namespace mir;
./tests/include/mir_test_framework/client_platform_factory.h: using namespace testing;
./tests/include/mir_test_framework/client_platform_factory.h: using namespace testing;
./src/server/scene/prompt_session_container.h:using namespace boost::multi_index;
./src/include/server/mir/frontend/template_protobuf_message_processor.h: using namespace std::literals::string_literals;
./include/test/mir/test/doubles/mock_window_manager.h: using namespace ::testing;

[Michał Sawicz (saviq)]

Syncing task from Mir.