Add tokens and entry points for KHR_blend_equation_advanced

src/gpu/gl/GrGLDefines.h

Index: src/gpu/gl/GrGLDefines.h
diff --git a/src/gpu/gl/GrGLDefines.h b/src/gpu/gl/GrGLDefines.h
index ae4050014ba902555a910fda37755bd582b7735a..511659c49211d639ef5402e309844afef1956f04 100644
--- a/src/gpu/gl/GrGLDefines.h
+++ b/src/gpu/gl/GrGLDefines.h
@@ -45,6 +45,28 @@
 /*      GL_GEQUAL */
 /*      GL_ALWAYS */
 
+/* Basic OpenGL blend equations */
+#define GR_GL_FUNC_ADD                       0x8006
+#define GR_GL_FUNC_SUBTRACT                  0x800A
+#define GR_GL_FUNC_REVERSE_SUBTRACT          0x800B
+
+/* GL_KHR_blend_equation_advanced */
+#define GR_GL_SCREEN                         0x9295
+#define GR_GL_OVERLAY                        0x9296
+#define GR_GL_DARKEN                         0x9297
+#define GR_GL_LIGHTEN                        0x9298
+#define GR_GL_COLORDODGE                     0x9299
+#define GR_GL_COLORBURN                      0x929A
+#define GR_GL_HARDLIGHT                      0x929B
+#define GR_GL_SOFTLIGHT                      0x929C
+#define GR_GL_DIFFERENCE                     0x929E
+#define GR_GL_EXCLUSION                      0x92A0
+#define GR_GL_MULTIPLY                       0x9294
+#define GR_GL_HSL_HUE                        0x92AD
+#define GR_GL_HSL_SATURATION                 0x92AE
+#define GR_GL_HSL_COLOR                      0x92AF
+#define GR_GL_HSL_LUMINOSITY                 0x92B0
+
 /* BlendingFactorDest */
 #define GR_GL_ZERO                           0
 #define GR_GL_ONE                            1