get genmipmap function in the struct

src/gpu/gl/GrGLCreateNullInterface.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "gl/GrGLInterface.h"
 #include "GrGLDefines.h"
@@ skipping 91 matching lines @@
 GrGLvoid GR_GL_FUNCTION_TYPE nullGLBindVertexArray(GrGLuint id) {}
 
 GrGLvoid GR_GL_FUNCTION_TYPE nullGLGenBuffers(GrGLsizei n, GrGLuint* ids) {
 
     for (int i = 0; i < n; ++i) {
         GrBufferObj* buffer = create_buffer();
         ids[i] = buffer->id();
     }
 }
 
+GrGLvoid GR_GL_FUNCTION_TYPE nullGLGenerateMipmap(GrGLenum target) {}
+
 GrGLvoid GR_GL_FUNCTION_TYPE nullGLBufferData(GrGLenum target,
                                               GrGLsizeiptr size,
                                               const GrGLvoid* data,
                                               GrGLenum usage) {
     GrGLuint id = 0;
 
     switch (target) {
     case GR_GL_ARRAY_BUFFER:
         id = gCurrArrayBuffer;
         break;
@@ skipping 177 matching lines @@
         interface->fDrawBuffer = noOpGLDrawBuffer;
         interface->fDrawBuffers = noOpGLDrawBuffers;
         interface->fDrawElements = noOpGLDrawElements;
         interface->fEnable = noOpGLEnable;
         interface->fEnableVertexAttribArray = noOpGLEnableVertexAttribArray;
         interface->fEndQuery = noOpGLEndQuery;
         interface->fFinish = noOpGLFinish;
         interface->fFlush = noOpGLFlush;
         interface->fFrontFace = noOpGLFrontFace;
         interface->fGenBuffers = nullGLGenBuffers;
+        interface->fGenerateMipmap = nullGLGenerateMipmap;
         interface->fGenQueries = noOpGLGenIds;
         interface->fGenTextures = noOpGLGenIds;
         interface->fGenVertexArrays = noOpGLGenIds;
         interface->fGetBufferParameteriv = nullGLGetBufferParameteriv;
         interface->fGetError = noOpGLGetError;
         interface->fGetIntegerv = noOpGLGetIntegerv;
         interface->fGetQueryObjecti64v = noOpGLGetQueryObjecti64v;
         interface->fGetQueryObjectiv = noOpGLGetQueryObjectiv;
         interface->fGetQueryObjectui64v = noOpGLGetQueryObjectui64v;
         interface->fGetQueryObjectuiv = noOpGLGetQueryObjectuiv;
@@ skipping 64 matching lines @@
         interface->fRenderbufferStorageMultisample = noOpGLRenderbufferStorageMultisample;
         interface->fBlitFramebuffer = noOpGLBlitFramebuffer;
         interface->fResolveMultisampleFramebuffer = noOpGLResolveMultisampleFramebuffer;
         interface->fMapBuffer = nullGLMapBuffer;
         interface->fUnmapBuffer = nullGLUnmapBuffer;
         interface->fBindFragDataLocationIndexed = noOpGLBindFragDataLocationIndexed;
     }
     glInterface.get()->ref();
     return glInterface.get();
 }