Change GLGetProcAddress typedef to function returning function pointer

ui/gl/gl_mock.h

 // Copyright (c) 2012 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.
 
 // This file implements mock GL Interface for unit testing. The interface
 // corresponds to the set of functionally distinct GL functions defined in
 // generate_bindings.py, which may originate from either desktop GL or GLES.
 
 #ifndef UI_GL_GL_MOCK_H_
 #define UI_GL_GL_MOCK_H_
 
 #include "testing/gmock/include/gmock/gmock.h"
 #include "ui/gl/gl_bindings.h"
 
 namespace gl {
 
+using GLFunctionPointerType = void (*)();
+
 class MockGLInterface {
  public:
   MockGLInterface();
   virtual ~MockGLInterface();
 
   // Set the functions called from the mock GL implementation for the purposes
   // of testing.
   static void SetGLInterface(MockGLInterface* gl_interface);
 
   // Find an entry point to the mock GL implementation.
-  static void* GL_BINDING_CALL GetGLProcAddress(const char* name);
+  static GLFunctionPointerType GL_BINDING_CALL
+  GetGLProcAddress(const char* name);
 
   // Include the auto-generated parts of this class. We split this because
   // it means we can easily edit the non-auto generated parts right here in
   // this file instead of having to edit some template or the code generator.
 
   // Member functions
   #include "gl_mock_autogen_gl.h"
 
   // TODO(zmo): crbug.com/456340
   // Functions that cannot be mocked because they have more than 10 args.
@@ skipping 79 matching lines @@
   #include "gl_bindings_autogen_mock.h"
 
   static void GL_BINDING_CALL Mock_glTexSubImage3DNoData(
       GLenum target, GLint level, GLint xoffset, GLint yoffset, GLint zoffset,
       GLsizei width, GLsizei height, GLsizei depth, GLenum format, GLenum type);
 };
 
 }  // namespace gl
 
 #endif  // UI_GL_GL_MOCK_H_