Move navigations with POST or referrer to the shell.

mojo/common/user_agent.h

Index: mojo/common/user_agent.h
diff --git a/mojo/common/user_agent.h b/mojo/common/user_agent.h
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index 0000000000000000000000000000000000000000..741ef8f590ad0ebeea78852abbacf6a3ab149da7
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+++ b/mojo/common/user_agent.h
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+// 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.
+
+#ifndef MOJO_COMMON_USER_AGENT_H_
+#define MOJO_COMMON_USER_AGENT_H_
+
+#include <string>
+
+#include "mojo/common/mojo_common_export.h"
+
+namespace mojo {
+namespace common {
+
+std::string GetUserAgent();
+
+}  // namespace common
+}  // namespace mojo
+
+#endif  // MOJO_COMMON_USER_AGENT_H_