Add GL indirect drawing APIs

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1666803002

Review URL: https://codereview.chromium.org/1666803002
diff --git a/src/gpu/gl/GrGLDefines.h b/src/gpu/gl/GrGLDefines.h
index a759413..9be769f 100644
--- a/src/gpu/gl/GrGLDefines.h
+++ b/src/gpu/gl/GrGLDefines.h
@@ -108,8 +108,10 @@
 /* Buffer Objects */
 #define GR_GL_ARRAY_BUFFER                   0x8892
 #define GR_GL_ELEMENT_ARRAY_BUFFER           0x8893
+#define GR_GL_DRAW_INDIRECT_BUFFER           0x8F3F
 #define GR_GL_ARRAY_BUFFER_BINDING           0x8894
 #define GR_GL_ELEMENT_ARRAY_BUFFER_BINDING   0x8895
+#define GR_GL_DRAW_INDIRECT_BUFFER_BINDING   0x8F43
 #define GR_GL_PIXEL_PACK_BUFFER              0x88EB
 #define GR_GL_PIXEL_UNPACK_BUFFER            0x88EC