BASE_EXPORT 12 base/base_export.h #define BASE_EXPORT __declspec(dllexport) BASE_EXPORT 15 base/base_export.h #define BASE_EXPORT __declspec(dllimport) BASE_EXPORT 21 base/base_export.h #define BASE_EXPORT __attribute__((visibility("default"))) BASE_EXPORT 24 base/base_export.h #define BASE_EXPORT BASE_EXPORT 30 base/base_export.h #define BASE_EXPORT