Mojo: Move C gles2 header files to mojo/public/c/gles2.

mojo/public/gles2/gles2_cpp.h

 // Copyright 2014 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.
 
 #ifndef MOJO_PUBLIC_GLES2_GLES2_CPP_H_
 #define MOJO_PUBLIC_GLES2_GLES2_CPP_H_
 
+#include "mojo/public/c/gles2/gles2.h"
 #include "mojo/public/cpp/environment/default_async_waiter.h"
-#include "mojo/public/gles2/gles2.h"
 
 namespace mojo {
 
 class GLES2Initializer {
  public:
   explicit GLES2Initializer(
       MojoAsyncWaiter* async_waiter = GetDefaultAsyncWaiter()) {
     MojoGLES2Initialize(async_waiter);
   }
   ~GLES2Initializer() { MojoGLES2Terminate(); }
 };
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_GLES2_GLES2_H_