Framework to allow Chromoting host to respect NAT traversal policy in linux.

remoting/host/plugin/policy_hack/nat_policy.h

Index: remoting/host/plugin/policy_hack/nat_policy.h
diff --git a/remoting/host/plugin/policy_hack/nat_policy.h b/remoting/host/plugin/policy_hack/nat_policy.h
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+// Copyright (c) 2011 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 REMOTING_HOST_PLUGIN_POLICY_HACK_NAT_POLICY_H_
+#define REMOTING_HOST_PLUGIN_POLICY_HACK_NAT_POLICY_H_
+
+#include "base/callback.h"
+#include "base/memory/ref_counted.h"
+
+namespace base {
+class MessageLoopProxy;
+class WaitableEvent;
+}  // namespace base
+
+namespace remoting {
+namespace policy_hack {
+
+// Watches for changes to the managed remote access host NAT policies.
+// If StartWatching() has been called, then before this object can be deleted,
+// StopWatching() have completed (the provided |done| event must be signaled).
+class NatPolicy {
+ public:
+  // Called with the current status of whether or not NAT traversal is enabled.
+  typedef base::Callback<void(bool)> NatEnabledCallback;
+
+  NatPolicy() {}
+  virtual ~NatPolicy() {}
+
+  // This guarantees that the |nat_enabled_cb| is called at least once with
+  // the current policy.  After that, |nat_enabled_cb| will be called whenever
+  // a change to the nat policy is detected.
+  virtual void StartWatching(const NatEnabledCallback& nat_enabled_cb) = 0;
+
+  // Should be called after StartWatching() before the object is deleted. Calls
+  // just wait for |done| to be signaled before deleting the object.
+  virtual void StopWatching(base::WaitableEvent* done) = 0;
+
+  // Implemented by each platform.  This message loop should be an IO message
+  // loop on linux.
+  //
+  // TODO(ajwong): figure out the right message loop for win/mac.
+  static NatPolicy* Create(base::MessageLoopProxy* message_loop_proxy);
+};
+
+}  // namespace policy_hack
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_PLUGIN_POLICY_HACK_NAT_POLICY_H_