Change GLGetProcAddress typedef to function returning function pointer

ui/gl/gl_api_unittest.cc

 // Copyright 2015 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.
 
 #include <stdint.h>
 
 #include <memory>
 
 #include "base/command_line.h"
 #include "base/macros.h"
@@ skipping 33 matching lines @@
     num_fake_extension_strings_ = 0;
     fake_extension_strings_ = nullptr;
 
     DCHECK(!g_current_gl_context_tls);
     g_current_gl_context_tls = new base::ThreadLocalPointer<GLApi>;
 
     SetGLGetProcAddressProc(
         static_cast<GLGetProcAddressProc>(&FakeGLGetProcAddress));
   }
 
-  static void* GL_BINDING_CALL FakeGLGetProcAddress(const char *proc) {
-    return reinterpret_cast<void*>(0x1);
+  static GLFunctionPointerType GL_BINDING_CALL
+  FakeGLGetProcAddress(const char* proc) {
+    return reinterpret_cast<GLFunctionPointerType>(0x1);
   }
 
   void TearDown() override {
     api_.reset(nullptr);
     delete g_current_gl_context_tls;
     g_current_gl_context_tls = nullptr;
 
     SetGLImplementation(kGLImplementationNone);
     fake_extension_string_ = "";
     fake_version_string_ = "";
@@ skipping 145 matching lines @@
                                  kFakeDisabledExtensions);
   InitializeAPI(&command_line);
 
   EXPECT_EQ(arraysize(kFilteredExtensions), GetNumExtensions());
   for (uint32_t i = 0; i < arraysize(kFilteredExtensions); ++i) {
     EXPECT_STREQ(kFilteredExtensions[i], GetExtensioni(i));
   }
 }
 
 }  // namespace gl