Let DoMapBufferRange write the result integer to signal a GL error.

gpu/command_buffer/service/gles2_cmd_decoder_passthrough_doer_prototypes.h

 // Copyright (c) 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 error::Error DoActiveTexture(GLenum texture);
 error::Error DoAttachShader(GLuint program, GLuint shader);
 error::Error DoBindAttribLocation(GLuint program,
                                   GLuint index,
                                   const char* name);
 error::Error DoBindBuffer(GLenum target, GLuint buffer);
@@ skipping 700 matching lines @@
                                            GLenum type,
                                            GLuint offset,
                                            uint32_t* result);
 error::Error DoEnableFeatureCHROMIUM(const char* feature);
 error::Error DoMapBufferRange(GLenum target,
                               GLintptr offset,
                               GLsizeiptr size,
                               GLbitfield access,
                               void* ptr,
                               int32_t data_shm_id,
-                              uint32_t data_shm_offset);
+                              uint32_t data_shm_offset,
+                              uint32_t* result);
 error::Error DoUnmapBuffer(GLenum target);
 error::Error DoResizeCHROMIUM(GLuint width,
                               GLuint height,
                               GLfloat scale_factor,
                               GLboolean alpha);
 error::Error DoGetRequestableExtensionsCHROMIUM(const char** extensions);
 error::Error DoRequestExtensionCHROMIUM(const char* extension);
 error::Error DoGetProgramInfoCHROMIUM(GLuint program,
                                       std::vector<uint8_t>* data);
 error::Error DoGetUniformBlocksCHROMIUM(GLuint program,
@@ skipping 235 matching lines @@
 
 error::Error DoOverlayPromotionHintCHROMIUM(GLuint texture,
                                             GLboolean promotion_hint,
                                             GLint display_x,
                                             GLint display_y);
 error::Error DoSetDrawRectangleCHROMIUM(GLint x,
                                         GLint y,
                                         GLint width,
                                         GLint height);
 error::Error DoSetEnableDCLayersCHROMIUM(GLboolean enable);