mojo: Convert gles2 to the new thunking system

mojo/public/platform/native/system_thunks.cc

 // Copyright 2013 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 "mojo/public/platform/native/system_thunks.h"
 
 #include <assert.h>
 
+#include "mojo/public/platform/native/thunk_export.h"
+
 extern "C" {
 
 static MojoSystemThunks g_thunks = {0};
 
 MojoTimeTicks MojoGetTimeTicksNow() {
   assert(g_thunks.GetTimeTicksNow);
   return g_thunks.GetTimeTicksNow();
 }
 
 MojoResult MojoClose(MojoHandle handle) {
@@ skipping 126 matching lines @@
                          MojoMapBufferFlags flags) {
   assert(g_thunks.MapBuffer);
   return g_thunks.MapBuffer(buffer_handle, offset, num_bytes, buffer, flags);
 }
 
 MojoResult MojoUnmapBuffer(void* buffer) {
   assert(g_thunks.UnmapBuffer);
   return g_thunks.UnmapBuffer(buffer);
 }
 
-// Call this function by looking
-// Always export this api.
-#if defined(WIN32)
-#define THUNK_EXPORT __declspec(dllexport)
-#else
-#define THUNK_EXPORT __attribute__((visibility("default")))
-#endif
-
 extern "C" THUNK_EXPORT size_t MojoSetSystemThunks(
     const MojoSystemThunks* system_thunks) {
   if (system_thunks->size >= sizeof(g_thunks))
     g_thunks = *system_thunks;
   return sizeof(g_thunks);
 }
 
 }  // extern "C"