GL_COVERAGE_SAMPLES_NV  491 ppapi/lib/gl/include/GLES2/gl2ext.h #define GL_COVERAGE_SAMPLES_NV                                  0x8ED4
GL_COVERAGE_SAMPLES_NV 1221 third_party/khronos/GLES2/gl2ext.h #define GL_COVERAGE_SAMPLES_NV            0x8ED4