Mojo: Move public/environment to public/cpp/environment.

mojo/environment/environment.cc

 // 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.
 
-#include "mojo/public/environment/environment.h"
+#include "mojo/public/cpp/environment/environment.h"
 
 namespace mojo {
 
 // These methods do nothing as we rely on LazyInstance<T> to instantiate all of
 // our global state in this implementation of the environment library.
 
 Environment::Environment() {
   // no-op
 }
 
 Environment::~Environment() {
   // no-op
 }
 
 }  // namespace mojo