Implement instanced rendering for simple shapes

src/gpu/gl/GrGLTestInterface.h

Index: src/gpu/gl/GrGLTestInterface.h
diff --git a/src/gpu/gl/GrGLTestInterface.h b/src/gpu/gl/GrGLTestInterface.h
index 936d9b8a97d53b7346182a6f431263b2ecdd832c..4df59235aecd6c6e6c90e6399203bd13f11e8306 100644
--- a/src/gpu/gl/GrGLTestInterface.h
+++ b/src/gpu/gl/GrGLTestInterface.h
@@ -65,7 +65,7 @@ public:
     virtual GrGLvoid drawBuffers(GrGLsizei n, const GrGLenum* bufs) {}
     virtual GrGLvoid drawElements(GrGLenum mode, GrGLsizei count, GrGLenum type, const GrGLvoid* indices) {}
     virtual GrGLvoid drawElementsInstanced(GrGLenum mode, GrGLsizei count, GrGLenum type, const GrGLvoid *indices, GrGLsizei primcount) {}
-    virtual GrGLvoid drawElementsIndirect(GrGLenum mode, GrGLenum type, GrGLvoid* indirect) {}
+    virtual GrGLvoid drawElementsIndirect(GrGLenum mode, GrGLenum type, const GrGLvoid* indirect) {}
     virtual GrGLvoid enable(GrGLenum cap) {}
     virtual GrGLvoid enableVertexAttribArray(GrGLuint index) {}
     virtual GrGLvoid endQuery(GrGLenum target) {}